diff --git a/src/backend/distributed/commands/multi_copy.c b/src/backend/distributed/commands/multi_copy.c
index 69a9fc3c9..05bcf8432 100644
--- a/src/backend/distributed/commands/multi_copy.c
+++ b/src/backend/distributed/commands/multi_copy.c
@@ -2101,12 +2101,6 @@ CitusCopyDestReceiverStartup(DestReceiver *dest, int operation,
 	copyDest->distributedRelation = distributedRelation;
 	copyDest->tupleDescriptor = inputTupleDescriptor;
 
-	/* we don't support copy to reference tables from workers */
-	if (partitionMethod == DISTRIBUTE_BY_NONE)
-	{
-		EnsureCoordinator();
-	}
-
 	/* load the list of shards and verify that we have shards to copy into */
 	shardIntervalList = LoadShardIntervalList(tableId);
 	if (shardIntervalList == NIL)
@@ -2147,7 +2141,7 @@ CitusCopyDestReceiverStartup(DestReceiver *dest, int operation,
 	 * Prevent concurrent UPDATE/DELETE on replication factor >1
 	 * (see AcquireExecutorMultiShardLocks() at multi_router_executor.c)
 	 */
-	LockShardListResources(shardIntervalList, RowExclusiveLock);
+	SerializeNonCommutativeWrites(shardIntervalList, RowExclusiveLock);
 
 	/* keep the table metadata to avoid looking it up for every tuple */
 	copyDest->tableMetadata = cacheEntry;
diff --git a/src/backend/distributed/executor/multi_router_executor.c b/src/backend/distributed/executor/multi_router_executor.c
index d95df4a6d..572556097 100644
--- a/src/backend/distributed/executor/multi_router_executor.c
+++ b/src/backend/distributed/executor/multi_router_executor.c
@@ -32,7 +32,9 @@
 #include "distributed/deparse_shard_query.h"
 #include "distributed/listutils.h"
 #include "distributed/master_metadata_utility.h"
+#include "distributed/master_protocol.h"
 #include "distributed/metadata_cache.h"
+#include "distributed/metadata_sync.h"
 #include "distributed/multi_executor.h"
 #include "distributed/multi_partitioning_utils.h"
 #include "distributed/multi_physical_planner.h"
@@ -248,7 +250,9 @@ AcquireExecutorShardLock(Task *task, CmdType commandType)
 
 	if (shardId != INVALID_SHARD_ID && lockMode != NoLock)
 	{
-		LockShardResource(shardId, lockMode);
+		ShardInterval *shardInterval = LoadShardInterval(shardId);
+
+		SerializeNonCommutativeWrites(list_make1(shardInterval), lockMode);
 	}
 
 	/*
@@ -282,8 +286,6 @@ AcquireExecutorShardLock(Task *task, CmdType commandType)
 			if (PartitionMethod(relationId) == DISTRIBUTE_BY_NONE)
 			{
 				List *shardIntervalList = LoadShardIntervalList(relationId);
-				ShardInterval *referenceTableShardInterval = (ShardInterval *) linitial(
-					shardIntervalList);
 
 				if (rowLockStrength == LCS_FORKEYSHARE || rowLockStrength == LCS_FORSHARE)
 				{
@@ -295,7 +297,7 @@ AcquireExecutorShardLock(Task *task, CmdType commandType)
 					rowLockMode = ExclusiveLock;
 				}
 
-				LockShardResource(referenceTableShardInterval->shardId, rowLockMode);
+				SerializeNonCommutativeWrites(shardIntervalList, rowLockMode);
 			}
 		}
 	}
diff --git a/src/backend/distributed/master/master_repair_shards.c b/src/backend/distributed/master/master_repair_shards.c
index 40ecce5a4..666505e61 100644
--- a/src/backend/distributed/master/master_repair_shards.c
+++ b/src/backend/distributed/master/master_repair_shards.c
@@ -24,6 +24,7 @@
 #include "distributed/listutils.h"
 #include "distributed/master_protocol.h"
 #include "distributed/metadata_cache.h"
+#include "distributed/metadata_sync.h"
 #include "distributed/multi_router_executor.h"
 #include "distributed/resource_lock.h"
 #include "distributed/worker_manager.h"
@@ -123,6 +124,54 @@ master_move_shard_placement(PG_FUNCTION_ARGS)
 }
 
 
+/*
+ * BlockWritesToShardList blocks writes to all shards in the given shard
+ * list. The function assumes that all the shards in the list are colocated.
+ */
+void
+BlockWritesToShardList(List *shardList)
+{
+	ListCell *shardCell = NULL;
+
+	bool shouldSyncMetadata = false;
+	ShardInterval *firstShardInterval = NULL;
+	Oid firstDistributedTableId = InvalidOid;
+
+	foreach(shardCell, shardList)
+	{
+		ShardInterval *shard = (ShardInterval *) lfirst(shardCell);
+
+		/*
+		 * We need to lock the referenced reference table metadata to avoid
+		 * asynchronous shard copy in case of cascading DML operations.
+		 */
+		LockReferencedReferenceShardDistributionMetadata(shard->shardId,
+														 ExclusiveLock);
+
+		LockShardDistributionMetadata(shard->shardId, ExclusiveLock);
+	}
+
+	/* following code relies on the list to have at least one shard */
+	if (list_length(shardList) == 0)
+	{
+		return;
+	}
+
+	/*
+	 * Since the function assumes that the input shards are colocated,
+	 * calculating shouldSyncMetadata for a single table is sufficient.
+	 */
+	firstShardInterval = (ShardInterval *) linitial(shardList);
+	firstDistributedTableId = firstShardInterval->relationId;
+
+	shouldSyncMetadata = ShouldSyncTableMetadata(firstDistributedTableId);
+	if (shouldSyncMetadata)
+	{
+		LockShardListMetadataOnWorkers(ExclusiveLock, shardList);
+	}
+}
+
+
 /*
  * LookupShardTransferMode maps the oids of citus.shard_transfer_mode enum
  * values to a char.
diff --git a/src/backend/distributed/metadata/metadata_sync.c b/src/backend/distributed/metadata/metadata_sync.c
index 5ae91eeb4..4adde5852 100644
--- a/src/backend/distributed/metadata/metadata_sync.c
+++ b/src/backend/distributed/metadata/metadata_sync.c
@@ -183,6 +183,31 @@ stop_metadata_sync_to_node(PG_FUNCTION_ARGS)
 }
 
 
+/*
+ * ClusterHasKnownMetadataWorkers returns true if the node executing the function
+ * knows at least one worker with metadata. We do it
+ * (a) by checking the node that executes the function is a worker with metadata
+ * (b) the coordinator knows at least one worker with metadata.
+ */
+bool
+ClusterHasKnownMetadataWorkers()
+{
+	bool workerWithMetadata = false;
+
+	if (GetLocalGroupId() != 0)
+	{
+		workerWithMetadata = true;
+	}
+
+	if (workerWithMetadata || HasMetadataWorkers())
+	{
+		return true;
+	}
+
+	return false;
+}
+
+
 /*
  * ShouldSyncTableMetadata checks if the metadata of a distributed table should be
  * propagated to metadata workers, i.e. the table is an MX table or reference table.
diff --git a/src/backend/distributed/planner/multi_router_planner.c b/src/backend/distributed/planner/multi_router_planner.c
index b43f5ea4f..4269a2e24 100644
--- a/src/backend/distributed/planner/multi_router_planner.c
+++ b/src/backend/distributed/planner/multi_router_planner.c
@@ -526,7 +526,6 @@ ModifyQuerySupported(Query *queryTree, Query *originalQuery, bool multiShardQuer
 	Oid distributedTableId = ExtractFirstDistributedTableId(queryTree);
 	uint32 rangeTableId = 1;
 	Var *partitionColumn = PartitionColumn(distributedTableId, rangeTableId);
-	bool isCoordinator = IsCoordinator();
 	List *rangeTableList = NIL;
 	ListCell *rangeTableCell = NULL;
 	uint32 queryTableCount = 0;
@@ -586,12 +585,9 @@ ModifyQuerySupported(Query *queryTree, Query *originalQuery, bool multiShardQuer
 	foreach(rangeTableCell, rangeTableList)
 	{
 		RangeTblEntry *rangeTableEntry = (RangeTblEntry *) lfirst(rangeTableCell);
-		bool referenceTable = false;
 
 		if (rangeTableEntry->rtekind == RTE_RELATION)
 		{
-			DistTableCacheEntry *distTableEntry = NULL;
-
 			if (!IsDistributedTable(rangeTableEntry->relid))
 			{
 				StringInfo errorMessage = makeStringInfo();
@@ -604,22 +600,6 @@ ModifyQuerySupported(Query *queryTree, Query *originalQuery, bool multiShardQuer
 									 errorMessage->data, NULL, NULL);
 			}
 
-			distTableEntry = DistributedTableCacheEntry(rangeTableEntry->relid);
-			if (distTableEntry->partitionMethod == DISTRIBUTE_BY_NONE)
-			{
-				referenceTable = true;
-			}
-
-			if (referenceTable && !isCoordinator)
-			{
-				return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-									 "cannot perform distributed planning for the given"
-									 " modification",
-									 "Modifications to reference tables are "
-									 "supported only from the coordinator.",
-									 NULL);
-			}
-
 			queryTableCount++;
 
 			/* we do not expect to see a view in modify query */
@@ -2843,12 +2823,6 @@ MultiRouterPlannableQuery(Query *query, RelationRestrictionContext *restrictionC
 				uint32 tableReplicationFactor = TableShardReplicationFactor(
 					distributedTableId);
 
-				if (partitionMethod == DISTRIBUTE_BY_NONE)
-				{
-					EnsureCoordinator();
-				}
-
-
 				if (tableReplicationFactor > 1 && partitionMethod != DISTRIBUTE_BY_NONE)
 				{
 					return false;
diff --git a/src/backend/distributed/transaction/worker_transaction.c b/src/backend/distributed/transaction/worker_transaction.c
index a695437cd..e1f3224cb 100644
--- a/src/backend/distributed/transaction/worker_transaction.c
+++ b/src/backend/distributed/transaction/worker_transaction.c
@@ -20,6 +20,7 @@
 
 #include "access/xact.h"
 #include "distributed/connection_management.h"
+#include "distributed/listutils.h"
 #include "distributed/metadata_cache.h"
 #include "distributed/multi_shard_transaction.h"
 #include "distributed/resource_lock.h"
@@ -55,6 +56,30 @@ SendCommandToWorker(char *nodeName, int32 nodePort, char *command)
 }
 
 
+/*
+ * SendCommandToFirstWorker sends the given command only to the first worker node
+ * sorted by host name and port number using SendCommandToWorker.
+ */
+void
+SendCommandToFirstWorker(char *command)
+{
+	List *workerNodeList = ActivePrimaryNodeList();
+	WorkerNode *firstWorkerNode = NULL;
+
+	workerNodeList = SortList(workerNodeList, CompareWorkerNodes);
+
+	if (list_length(workerNodeList) == 0)
+	{
+		ereport(ERROR, (errmsg("cannot find a worker node")));
+	}
+
+	firstWorkerNode = (WorkerNode *) linitial(workerNodeList);
+
+	SendCommandToWorker(firstWorkerNode->workerName, firstWorkerNode->workerPort,
+						command);
+}
+
+
 /*
  * SendCommandToWorkers sends a command to all workers in
  * parallel. Commands are committed on the workers when the local
diff --git a/src/backend/distributed/utils/reference_table_utils.c b/src/backend/distributed/utils/reference_table_utils.c
index 0a1d62cd8..99a94ba19 100644
--- a/src/backend/distributed/utils/reference_table_utils.c
+++ b/src/backend/distributed/utils/reference_table_utils.c
@@ -128,7 +128,9 @@ void
 ReplicateAllReferenceTablesToNode(char *nodeName, int nodePort)
 {
 	List *referenceTableList = ReferenceTableOidList();
+	List *referenceShardIntervalList = NIL;
 	ListCell *referenceTableCell = NULL;
+	ListCell *referenceShardIntervalCell = NULL;
 	List *workerNodeList = ActivePrimaryNodeList();
 	uint32 workerCount = 0;
 	Oid firstReferenceTableId = InvalidOid;
@@ -150,6 +152,20 @@ ReplicateAllReferenceTablesToNode(char *nodeName, int nodePort)
 		Oid referenceTableId = lfirst_oid(referenceTableCell);
 		List *shardIntervalList = LoadShardIntervalList(referenceTableId);
 		ShardInterval *shardInterval = (ShardInterval *) linitial(shardIntervalList);
+
+		referenceShardIntervalList = lappend(referenceShardIntervalList,
+											 shardInterval);
+	}
+
+	if (ClusterHasKnownMetadataWorkers())
+	{
+		BlockWritesToShardList(referenceShardIntervalList);
+	}
+
+	foreach(referenceShardIntervalCell, referenceShardIntervalList)
+	{
+		ShardInterval *shardInterval = (ShardInterval *) lfirst(
+			referenceShardIntervalCell);
 		uint64 shardId = shardInterval->shardId;
 
 		LockShardDistributionMetadata(shardId, ExclusiveLock);
@@ -394,6 +410,7 @@ void
 DeleteAllReferenceTablePlacementsFromNodeGroup(uint32 groupId)
 {
 	List *referenceTableList = ReferenceTableOidList();
+	List *referenceShardIntervalList = NIL;
 	ListCell *referenceTableCell = NULL;
 
 	/* if there are no reference tables, we do not need to do anything */
@@ -407,6 +424,13 @@ DeleteAllReferenceTablePlacementsFromNodeGroup(uint32 groupId)
 	 * DeleteAllReferenceTablePlacementsFromNodeGroup calls.
 	 */
 	referenceTableList = SortList(referenceTableList, CompareOids);
+	if (ClusterHasKnownMetadataWorkers())
+	{
+		referenceShardIntervalList = GetSortedReferenceShardIntervals(referenceTableList);
+
+		BlockWritesToShardList(referenceShardIntervalList);
+	}
+
 	foreach(referenceTableCell, referenceTableList)
 	{
 		GroupShardPlacement *placement = NULL;
diff --git a/src/backend/distributed/utils/resource_lock.c b/src/backend/distributed/utils/resource_lock.c
index 06fd61a99..aa6dc2018 100644
--- a/src/backend/distributed/utils/resource_lock.c
+++ b/src/backend/distributed/utils/resource_lock.c
@@ -20,7 +20,9 @@
 #include "distributed/colocation_utils.h"
 #include "distributed/listutils.h"
 #include "distributed/master_metadata_utility.h"
+#include "distributed/master_protocol.h"
 #include "distributed/metadata_cache.h"
+#include "distributed/metadata_sync.h"
 #include "distributed/multi_partitioning_utils.h"
 #include "distributed/distributed_planner.h"
 #include "distributed/multi_router_executor.h"
@@ -34,7 +36,10 @@
 
 /* local function forward declarations */
 static LOCKMODE IntToLockMode(int mode);
-static List * GetSortedReferenceShardIntervals(List *relationList);
+static void LockShardListResources(List *shardIntervalList, LOCKMODE lockMode);
+static void LockShardListResourcesOnFirstWorker(LOCKMODE lockmode,
+												List *shardIntervalList);
+static bool IsFirstWorkerNode();
 
 
 /* exports for SQL callable functions */
@@ -83,7 +88,7 @@ lock_shard_metadata(PG_FUNCTION_ARGS)
 
 
 /*
- * lock_shard_resources allows shard resources  to be locked
+ * lock_shard_resources allows shard resources to be locked
  * remotely to serialise non-commutative writes on shards.
  *
  * This function does not sort the array to avoid deadlock, callers
@@ -122,6 +127,111 @@ lock_shard_resources(PG_FUNCTION_ARGS)
 }
 
 
+/*
+ * LockShardListResourcesOnFirstWorker acquires the resource locks for the specified
+ * shards on the first worker. Acquiring a lock with or without metadata does not
+ * matter for us. So, worker does not have to be an MX node, acquiring the lock
+ * on any worker node is enough. Note that the function does not sort the shard list,
+ * therefore the caller should sort the shard list in order to avoid deadlocks.
+ */
+static void
+LockShardListResourcesOnFirstWorker(LOCKMODE lockmode, List *shardIntervalList)
+{
+	StringInfo lockCommand = makeStringInfo();
+	ListCell *shardIntervalCell = NULL;
+	int processedShardIntervalCount = 0;
+	int totalShardIntervalCount = list_length(shardIntervalList);
+
+	appendStringInfo(lockCommand, "SELECT lock_shard_resources(%d, ARRAY[", lockmode);
+
+	foreach(shardIntervalCell, shardIntervalList)
+	{
+		ShardInterval *shardInterval = (ShardInterval *) lfirst(shardIntervalCell);
+		int64 shardId = shardInterval->shardId;
+
+		appendStringInfo(lockCommand, "%lu", shardId);
+
+		processedShardIntervalCount++;
+		if (processedShardIntervalCount != totalShardIntervalCount)
+		{
+			appendStringInfo(lockCommand, ", ");
+		}
+	}
+
+	appendStringInfo(lockCommand, "])");
+
+	SendCommandToFirstWorker(lockCommand->data);
+}
+
+
+/*
+ * IsFirstWorkerNode checks whether the node is the first worker node sorted
+ * according to the host name and port number.
+ */
+static bool
+IsFirstWorkerNode()
+{
+	List *workerNodeList = ActivePrimaryNodeList();
+	WorkerNode *firstWorkerNode = NULL;
+
+	workerNodeList = SortList(workerNodeList, CompareWorkerNodes);
+
+	if (list_length(workerNodeList) == 0)
+	{
+		return false;
+	}
+
+	firstWorkerNode = (WorkerNode *) linitial(workerNodeList);
+
+	if (firstWorkerNode->groupId == GetLocalGroupId())
+	{
+		return true;
+	}
+
+	return false;
+}
+
+
+/*
+ * LockShardListMetadataOnWorkers acquires the matadata locks for the specified shards on
+ * metadata workers. Note that the function does not sort the shard list, therefore the
+ * caller should sort the shard list in order to avoid deadlocks.
+ */
+void
+LockShardListMetadataOnWorkers(LOCKMODE lockmode, List *shardIntervalList)
+{
+	StringInfo lockCommand = makeStringInfo();
+	ListCell *shardIntervalCell = NULL;
+	int processedShardIntervalCount = 0;
+	int totalShardIntervalCount = list_length(shardIntervalList);
+
+	if (list_length(shardIntervalList) == 0)
+	{
+		return;
+	}
+
+	appendStringInfo(lockCommand, "SELECT lock_shard_metadata(%d, ARRAY[", lockmode);
+
+	foreach(shardIntervalCell, shardIntervalList)
+	{
+		ShardInterval *shardInterval = (ShardInterval *) lfirst(shardIntervalCell);
+		int64 shardId = shardInterval->shardId;
+
+		appendStringInfo(lockCommand, "%lu", shardId);
+
+		processedShardIntervalCount++;
+		if (processedShardIntervalCount != totalShardIntervalCount)
+		{
+			appendStringInfo(lockCommand, ", ");
+		}
+	}
+
+	appendStringInfo(lockCommand, "])");
+
+	SendCommandToWorkers(WORKERS_WITH_METADATA, lockCommand->data);
+}
+
+
 /*
  * IntToLockMode verifies whether the specified integer is an accepted lock mode
  * and returns it as a LOCKMODE enum.
@@ -141,6 +251,10 @@ IntToLockMode(int mode)
 	{
 		return AccessShareLock;
 	}
+	else if (mode == RowExclusiveLock)
+	{
+		return RowExclusiveLock;
+	}
 	else
 	{
 		elog(ERROR, "unsupported lockmode %d", mode);
@@ -169,6 +283,9 @@ LockShardDistributionMetadata(int64 shardId, LOCKMODE lockMode)
 /*
  * LockReferencedReferenceShardDistributionMetadata acquires the given lock
  * on the reference tables which has a foreign key from the given relation.
+ *
+ * It also gets metadata locks on worker nodes to prevent concurrent write
+ * operations on reference tables from metadata nodes.
  */
 void
 LockReferencedReferenceShardDistributionMetadata(uint64 shardId, LOCKMODE lock)
@@ -178,8 +295,13 @@ LockReferencedReferenceShardDistributionMetadata(uint64 shardId, LOCKMODE lock)
 
 	DistTableCacheEntry *cacheEntry = DistributedTableCacheEntry(relationId);
 	List *referencedRelationList = cacheEntry->referencedRelationsViaForeignKey;
-
 	List *shardIntervalList = GetSortedReferenceShardIntervals(referencedRelationList);
+
+	if (list_length(shardIntervalList) > 0 && ClusterHasKnownMetadataWorkers())
+	{
+		LockShardListMetadataOnWorkers(lock, shardIntervalList);
+	}
+
 	foreach(shardIntervalCell, shardIntervalList)
 	{
 		ShardInterval *shardInterval = (ShardInterval *) lfirst(shardIntervalCell);
@@ -193,7 +315,7 @@ LockReferencedReferenceShardDistributionMetadata(uint64 shardId, LOCKMODE lock)
  * GetSortedReferenceShards iterates through the given relation list.
  * Lists the shards of reference tables and returns the list after sorting.
  */
-static List *
+List *
 GetSortedReferenceShardIntervals(List *relationList)
 {
 	List *shardIntervalList = NIL;
@@ -353,11 +475,43 @@ LockShardsInPlacementListMetadata(List *shardPlacementList, LOCKMODE lockMode)
 }
 
 
+/*
+ * SerializeNonCommutativeWrites acquires the required locks to prevent concurrent
+ * writes on the given shards.
+ *
+ * If the modified shard is a reference table's shard and the cluster is an MX
+ * cluster we need to get shard resource lock on the first worker node to
+ * prevent divergence possibility between placements of the reference table.
+ *
+ * In other workers, by acquiring a lock on the first worker, we're serializing
+ * non-commutative modifications to a reference table. If the node executing the
+ * command is the first worker, defined via IsFirstWorker(), we skip acquiring
+ * the lock remotely to avoid an extra round-trip and/or self-deadlocks.
+ *
+ * Finally, if we're not dealing with reference tables on MX cluster, we'll
+ * always acquire the lock with LockShardListResources() call.
+ */
+void
+SerializeNonCommutativeWrites(List *shardIntervalList, LOCKMODE lockMode)
+{
+	ShardInterval *firstShardInterval = (ShardInterval *) linitial(shardIntervalList);
+	int64 firstShardId = firstShardInterval->shardId;
+
+	if (ReferenceTableShardId(firstShardId) && ClusterHasKnownMetadataWorkers() &&
+		!IsFirstWorkerNode())
+	{
+		LockShardListResourcesOnFirstWorker(lockMode, shardIntervalList);
+	}
+
+	LockShardListResources(shardIntervalList, lockMode);
+}
+
+
 /*
  * LockShardListResources takes locks on all shards in shardIntervalList to
  * prevent concurrent DML statements on those shards.
  */
-void
+static void
 LockShardListResources(List *shardIntervalList, LOCKMODE lockMode)
 {
 	ListCell *shardIntervalCell = NULL;
diff --git a/src/include/distributed/metadata_sync.h b/src/include/distributed/metadata_sync.h
index 5a3b09c46..41b346ae9 100644
--- a/src/include/distributed/metadata_sync.h
+++ b/src/include/distributed/metadata_sync.h
@@ -18,6 +18,7 @@
 
 
 /* Functions declarations for metadata syncing */
+extern bool ClusterHasKnownMetadataWorkers(void);
 extern bool ShouldSyncTableMetadata(Oid relationId);
 extern List * MetadataCreateCommands(void);
 extern List * GetDistributedTableDDLEvents(Oid relationId);
diff --git a/src/include/distributed/resource_lock.h b/src/include/distributed/resource_lock.h
index a83519088..4d78966c0 100644
--- a/src/include/distributed/resource_lock.h
+++ b/src/include/distributed/resource_lock.h
@@ -13,6 +13,7 @@
 #include "postgres.h" /* IWYU pragma: keep */
 #include "c.h"
 
+#include "distributed/worker_transaction.h"
 #include "nodes/pg_list.h"
 #include "storage/lock.h"
 
@@ -66,6 +67,8 @@ typedef enum AdvisoryLocktagClass
 /* Lock shard/relation metadata for safe modifications */
 extern void LockShardDistributionMetadata(int64 shardId, LOCKMODE lockMode);
 extern bool TryLockShardDistributionMetadata(int64 shardId, LOCKMODE lockMode);
+extern void LockShardListMetadataOnWorkers(LOCKMODE lockmode, List *shardIntervalList);
+extern void BlockWritesToShardList(List *shardList);
 
 /* Lock shard/relation metadata of the referenced reference table if exists */
 extern void LockReferencedReferenceShardDistributionMetadata(uint64 shardId, LOCKMODE
@@ -83,8 +86,9 @@ extern void UnlockJobResource(uint64 jobId, LOCKMODE lockmode);
 extern void LockShardListMetadata(List *shardIntervalList, LOCKMODE lockMode);
 extern void LockShardsInPlacementListMetadata(List *shardPlacementList,
 											  LOCKMODE lockMode);
-extern void LockShardListResources(List *shardIntervalList, LOCKMODE lockMode);
+extern void SerializeNonCommutativeWrites(List *shardIntervalList, LOCKMODE lockMode);
 extern void LockRelationShardResources(List *relationShardList, LOCKMODE lockMode);
+extern List * GetSortedReferenceShardIntervals(List *relationList);
 
 /* Lock partitions of partitioned table */
 extern void LockPartitionsInRelationList(List *relationIdList, LOCKMODE lockmode);
diff --git a/src/include/distributed/worker_transaction.h b/src/include/distributed/worker_transaction.h
index a63f12a78..4c76f77ac 100644
--- a/src/include/distributed/worker_transaction.h
+++ b/src/include/distributed/worker_transaction.h
@@ -29,6 +29,7 @@ typedef enum TargetWorkerSet
 /* Functions declarations for worker transactions */
 extern List * GetWorkerTransactions(void);
 extern void SendCommandToWorker(char *nodeName, int32 nodePort, char *command);
+extern void SendCommandToFirstWorker(char *command);
 extern void SendCommandToWorkers(TargetWorkerSet targetWorkerSet, char *command);
 extern void SendBareCommandListToWorkers(TargetWorkerSet targetWorkerSet,
 										 List *commandList);
diff --git a/src/test/regress/expected/multi_mx_create_table.out b/src/test/regress/expected/multi_mx_create_table.out
index 7eff736b1..3cdccb5f2 100644
--- a/src/test/regress/expected/multi_mx_create_table.out
+++ b/src/test/regress/expected/multi_mx_create_table.out
@@ -2,6 +2,7 @@
 -- MULTI_MX_CREATE_TABLE
 --
 ALTER SEQUENCE pg_catalog.pg_dist_shardid_seq RESTART 1220000;
+ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART 1390000;
 SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
  start_metadata_sync_to_node 
 -----------------------------
@@ -474,20 +475,20 @@ ORDER BY colocationid, logicalrelid;
  mx_ddl_table                                           |            3 |           4 | h          | s
  app_analytics_events_mx                                |            3 |           4 | h          | s
  company_employees_mx                                   |            3 |           4 | h          | s
- nation_hash                                            |            4 |          16 | h          | s
- citus_mx_test_schema.nation_hash                       |            4 |          16 | h          | s
- lineitem_mx                                            |            5 |          16 | h          | s
- orders_mx                                              |            5 |          16 | h          | s
- customer_mx                                            |            6 |           1 | n          | t
- nation_mx                                              |            6 |           1 | n          | t
- part_mx                                                |            6 |           1 | n          | t
- supplier_mx                                            |            6 |           1 | n          | t
- limit_orders_mx                                        |            7 |           2 | h          | s
- articles_hash_mx                                       |            7 |           2 | h          | s
- multiple_hash_mx                                       |            8 |           2 | h          | s
- researchers_mx                                         |            9 |           2 | h          | s
- labs_mx                                                |           10 |           1 | h          | s
- objects_mx                                             |           10 |           1 | h          | s
- articles_single_shard_hash_mx                          |           10 |           1 | h          | s
+ customer_mx                                            |            4 |           1 | n          | t
+ nation_mx                                              |            4 |           1 | n          | t
+ part_mx                                                |            4 |           1 | n          | t
+ supplier_mx                                            |            4 |           1 | n          | t
+ nation_hash                                            |      1390000 |          16 | h          | s
+ citus_mx_test_schema.nation_hash                       |      1390000 |          16 | h          | s
+ lineitem_mx                                            |      1390001 |          16 | h          | s
+ orders_mx                                              |      1390001 |          16 | h          | s
+ limit_orders_mx                                        |      1390002 |           2 | h          | s
+ articles_hash_mx                                       |      1390002 |           2 | h          | s
+ multiple_hash_mx                                       |      1390003 |           2 | h          | s
+ researchers_mx                                         |      1390004 |           2 | h          | s
+ labs_mx                                                |      1390005 |           1 | h          | s
+ objects_mx                                             |      1390005 |           1 | h          | s
+ articles_single_shard_hash_mx                          |      1390005 |           1 | h          | s
 (23 rows)
 
diff --git a/src/test/regress/expected/multi_mx_modifications_to_reference_tables.out b/src/test/regress/expected/multi_mx_modifications_to_reference_tables.out
new file mode 100644
index 000000000..b8febf421
--- /dev/null
+++ b/src/test/regress/expected/multi_mx_modifications_to_reference_tables.out
@@ -0,0 +1,159 @@
+SET citus.next_shard_id TO 100400;
+-- =================================================================
+-- test modification functionality on reference tables from MX nodes
+-- =================================================================
+CREATE SCHEMA mx_modify_reference_table;
+SET search_path TO 'mx_modify_reference_table';
+SET citus.shard_count TO 4;
+SET citus.shard_replication_factor TO 1;
+SET citus.replication_model TO 'streaming';
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+ start_metadata_sync_to_node 
+-----------------------------
+ 
+(1 row)
+
+SELECT start_metadata_sync_to_node('localhost', :worker_2_port);
+ start_metadata_sync_to_node 
+-----------------------------
+ 
+(1 row)
+
+CREATE TABlE ref_table(id int, value_1 int);
+SELECT create_reference_table('ref_table');
+ create_reference_table 
+------------------------
+ 
+(1 row)
+
+CREATE TABlE ref_table_2(id int, value_1 int);
+SELECT create_reference_table('ref_table_2');
+ create_reference_table 
+------------------------
+ 
+(1 row)
+
+CREATE TABLE test_table_1(id int, value_1 int);
+SELECT create_distributed_table('test_table_1', 'id');
+ create_distributed_table 
+--------------------------
+ 
+(1 row)
+
+INSERT INTO test_table_1 VALUES(5,5),(6,6);
+\c - - - :worker_1_port
+SET search_path TO 'mx_modify_reference_table';
+-- Simple DML operations from the first worker node
+INSERT INTO ref_table VALUES(1,1),(2,2);
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+   3
+(1 row)
+
+UPDATE ref_table SET value_1 = 1 WHERE id = 2;
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+   2
+(1 row)
+
+DELETE FROM ref_table;
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+    
+(1 row)
+
+COPY ref_table FROM STDIN DELIMITER ',';
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+   3
+(1 row)
+
+-- Select For Update also follows the same logic with modification.
+-- It has been started to be supported on MX nodes with DML operations.
+SELECT * FROM ref_table FOR UPDATE;
+ id | value_1 
+----+---------
+  1 |       1
+  2 |       2
+(2 rows)
+
+-- Both distributed and non-distributed INSERT INTO ... SELECT
+-- queries are also supported on MX nodes.
+INSERT INTO ref_table SELECT * FROM test_table_1;
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+  14
+(1 row)
+
+INSERT INTO ref_table_2 SELECT * FROM ref_table;
+SELECT SUM(value_1) FROM ref_table_2;
+ sum 
+-----
+  14
+(1 row)
+
+-- Now connect to the second worker and observe the results as well
+\c - - - :worker_2_port
+SET search_path TO 'mx_modify_reference_table';
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+  14
+(1 row)
+
+SELECT SUM(value_1) FROM ref_table_2;
+ sum 
+-----
+  14
+(1 row)
+
+-- Run basic queries from second worker node. These tests have been added 
+-- since locking logic is slightly different between running these commands
+-- from first worker node and the second one
+INSERT INTO ref_table VALUES(1,1),(2,2);
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+  17
+(1 row)
+
+UPDATE ref_table SET value_1 = 1 WHERE id = 2;
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+  15
+(1 row)
+
+COPY ref_table FROM STDIN DELIMITER ',';
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+  18
+(1 row)
+
+INSERT INTO ref_table SELECT * FROM test_table_1;
+SELECT SUM(value_1) FROM ref_table;
+ sum 
+-----
+  29
+(1 row)
+
+INSERT INTO ref_table_2 SELECT * FROM ref_table;
+SELECT SUM(value_1) FROM ref_table_2;
+ sum 
+-----
+  43
+(1 row)
+
+\c - - - :master_port
+SET search_path TO 'public';
+DROP SCHEMA mx_modify_reference_table CASCADE;
+NOTICE:  drop cascades to 3 other objects
+DETAIL:  drop cascades to table mx_modify_reference_table.ref_table
+drop cascades to table mx_modify_reference_table.ref_table_2
+drop cascades to table mx_modify_reference_table.test_table_1
diff --git a/src/test/regress/expected/multi_mx_router_planner.out b/src/test/regress/expected/multi_mx_router_planner.out
index 0ba5f7c75..9ef20e5ff 100644
--- a/src/test/regress/expected/multi_mx_router_planner.out
+++ b/src/test/regress/expected/multi_mx_router_planner.out
@@ -931,11 +931,6 @@ SELECT *
  41 |         1 | aznavour     |      11814
 (5 rows)
 
--- SELECT ... FOR UPDATE does not supported from MX nodes if it contains
--- reference table.
-SELECT * FROM customer_mx FOR UPDATE;
-ERROR:  operation is not allowed on this node
-HINT:  Connect to the coordinator and run it again.
 -- not router plannable due to or
 SELECT *
 	FROM articles_hash_mx
diff --git a/src/test/regress/expected/multi_unsupported_worker_operations.out b/src/test/regress/expected/multi_unsupported_worker_operations.out
index 5a0b86c46..d46760e8a 100644
--- a/src/test/regress/expected/multi_unsupported_worker_operations.out
+++ b/src/test/regress/expected/multi_unsupported_worker_operations.out
@@ -108,35 +108,6 @@ SELECT count(*) FROM pg_dist_shard WHERE logicalrelid='mx_table'::regclass;
      5
 (1 row)
 
--- INSERT/UPDATE/DELETE/COPY on reference tables
-SELECT * FROM mx_ref_table ORDER BY col_1;
- col_1 | col_2  
--------+--------
-   -78 | sapien
-   -37 | morbi
-   -34 | augue
-(3 rows)
-
-INSERT INTO mx_ref_table (col_1, col_2) VALUES (-6, 'vestibulum');
-ERROR:  cannot perform distributed planning for the given modification
-DETAIL:  Modifications to reference tables are supported only from the coordinator.
-UPDATE mx_ref_table SET col_2 = 'habitant' WHERE col_1 = -37;
-ERROR:  cannot perform distributed planning for the given modification
-DETAIL:  Modifications to reference tables are supported only from the coordinator.
-DELETE FROM mx_ref_table WHERE col_1 = -78;
-ERROR:  cannot perform distributed planning for the given modification
-DETAIL:  Modifications to reference tables are supported only from the coordinator.
-COPY mx_ref_table (col_1, col_2) FROM STDIN WITH (FORMAT 'csv');
-ERROR:  operation is not allowed on this node
-HINT:  Connect to the coordinator and run it again.
-SELECT * FROM mx_ref_table ORDER BY col_1;
- col_1 | col_2  
--------+--------
-   -78 | sapien
-   -37 | morbi
-   -34 | augue
-(3 rows)
-
 \c - - - :master_port
 DROP TABLE mx_ref_table;
 CREATE UNIQUE INDEX mx_test_uniq_index ON mx_table(col_1);
diff --git a/src/test/regress/multi_mx_schedule b/src/test/regress/multi_mx_schedule
index 0484a27ee..3186c2ed4 100644
--- a/src/test/regress/multi_mx_schedule
+++ b/src/test/regress/multi_mx_schedule
@@ -18,8 +18,9 @@ test: multi_cluster_management
 test: multi_test_helpers
 
 # the following test has to be run sequentially
-test: multi_mx_hide_shard_names 
-test: multi_mx_partitioning 
+test: multi_mx_hide_shard_names
+test: multi_mx_modifications_to_reference_tables
+test: multi_mx_partitioning
 test: multi_mx_create_table
 test: multi_mx_copy_data multi_mx_router_planner
 test: multi_mx_schema_support multi_mx_tpch_query1 multi_mx_tpch_query10
diff --git a/src/test/regress/sql/multi_mx_create_table.sql b/src/test/regress/sql/multi_mx_create_table.sql
index f7ecac215..33e085fbf 100644
--- a/src/test/regress/sql/multi_mx_create_table.sql
+++ b/src/test/regress/sql/multi_mx_create_table.sql
@@ -3,6 +3,7 @@
 --
 
 ALTER SEQUENCE pg_catalog.pg_dist_shardid_seq RESTART 1220000;
+ALTER SEQUENCE pg_catalog.pg_dist_colocationid_seq RESTART 1390000;
 
 SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
 SELECT start_metadata_sync_to_node('localhost', :worker_2_port);
diff --git a/src/test/regress/sql/multi_mx_modifications_to_reference_tables.sql b/src/test/regress/sql/multi_mx_modifications_to_reference_tables.sql
new file mode 100644
index 000000000..470a9e084
--- /dev/null
+++ b/src/test/regress/sql/multi_mx_modifications_to_reference_tables.sql
@@ -0,0 +1,91 @@
+
+
+SET citus.next_shard_id TO 100400;
+
+-- =================================================================
+-- test modification functionality on reference tables from MX nodes
+-- =================================================================
+
+CREATE SCHEMA mx_modify_reference_table;
+SET search_path TO 'mx_modify_reference_table';
+
+SET citus.shard_count TO 4;
+SET citus.shard_replication_factor TO 1;
+
+SET citus.replication_model TO 'streaming';
+SELECT start_metadata_sync_to_node('localhost', :worker_1_port);
+SELECT start_metadata_sync_to_node('localhost', :worker_2_port);
+
+CREATE TABlE ref_table(id int, value_1 int);
+SELECT create_reference_table('ref_table');
+
+CREATE TABlE ref_table_2(id int, value_1 int);
+SELECT create_reference_table('ref_table_2');
+
+CREATE TABLE test_table_1(id int, value_1 int);
+SELECT create_distributed_table('test_table_1', 'id');
+INSERT INTO test_table_1 VALUES(5,5),(6,6);
+
+\c - - - :worker_1_port
+SET search_path TO 'mx_modify_reference_table';
+
+-- Simple DML operations from the first worker node
+INSERT INTO ref_table VALUES(1,1),(2,2);
+SELECT SUM(value_1) FROM ref_table;
+
+UPDATE ref_table SET value_1 = 1 WHERE id = 2;
+SELECT SUM(value_1) FROM ref_table;
+
+DELETE FROM ref_table;
+SELECT SUM(value_1) FROM ref_table;
+
+COPY ref_table FROM STDIN DELIMITER ',';
+1,1
+2,2
+\.
+SELECT SUM(value_1) FROM ref_table;
+
+-- Select For Update also follows the same logic with modification.
+-- It has been started to be supported on MX nodes with DML operations.
+SELECT * FROM ref_table FOR UPDATE;
+
+-- Both distributed and non-distributed INSERT INTO ... SELECT
+-- queries are also supported on MX nodes.
+INSERT INTO ref_table SELECT * FROM test_table_1;
+SELECT SUM(value_1) FROM ref_table;
+
+INSERT INTO ref_table_2 SELECT * FROM ref_table;
+SELECT SUM(value_1) FROM ref_table_2;
+
+-- Now connect to the second worker and observe the results as well
+\c - - - :worker_2_port
+SET search_path TO 'mx_modify_reference_table';
+
+SELECT SUM(value_1) FROM ref_table;
+SELECT SUM(value_1) FROM ref_table_2;
+
+-- Run basic queries from second worker node. These tests have been added 
+-- since locking logic is slightly different between running these commands
+-- from first worker node and the second one
+INSERT INTO ref_table VALUES(1,1),(2,2);
+SELECT SUM(value_1) FROM ref_table;
+
+UPDATE ref_table SET value_1 = 1 WHERE id = 2;
+SELECT SUM(value_1) FROM ref_table;
+
+COPY ref_table FROM STDIN DELIMITER ',';
+1,1
+2,2
+\.
+SELECT SUM(value_1) FROM ref_table;
+
+INSERT INTO ref_table SELECT * FROM test_table_1;
+SELECT SUM(value_1) FROM ref_table;
+
+INSERT INTO ref_table_2 SELECT * FROM ref_table;
+SELECT SUM(value_1) FROM ref_table_2;
+
+\c - - - :master_port
+
+SET search_path TO 'public';
+DROP SCHEMA mx_modify_reference_table CASCADE;
diff --git a/src/test/regress/sql/multi_mx_router_planner.sql b/src/test/regress/sql/multi_mx_router_planner.sql
index 8da234cc1..366f78092 100644
--- a/src/test/regress/sql/multi_mx_router_planner.sql
+++ b/src/test/regress/sql/multi_mx_router_planner.sql
@@ -407,10 +407,6 @@ SELECT *
 	FROM articles_hash_mx
 	WHERE author_id = (random()::int  * 0 + 1);
 
--- SELECT ... FOR UPDATE does not supported from MX nodes if it contains
--- reference table.
-SELECT * FROM customer_mx FOR UPDATE;
-
 -- not router plannable due to or
 SELECT *
 	FROM articles_hash_mx
diff --git a/src/test/regress/sql/multi_unsupported_worker_operations.sql b/src/test/regress/sql/multi_unsupported_worker_operations.sql
index 3b604ac0a..83ffc1808 100644
--- a/src/test/regress/sql/multi_unsupported_worker_operations.sql
+++ b/src/test/regress/sql/multi_unsupported_worker_operations.sql
@@ -79,15 +79,6 @@ SELECT count(*) FROM pg_dist_shard WHERE logicalrelid='mx_table'::regclass;
 INSERT INTO pg_dist_shard SELECT * FROM pg_dist_shard_temp;
 SELECT count(*) FROM pg_dist_shard WHERE logicalrelid='mx_table'::regclass;
 
-
--- INSERT/UPDATE/DELETE/COPY on reference tables
-SELECT * FROM mx_ref_table ORDER BY col_1;
-INSERT INTO mx_ref_table (col_1, col_2) VALUES (-6, 'vestibulum');
-UPDATE mx_ref_table SET col_2 = 'habitant' WHERE col_1 = -37;
-DELETE FROM mx_ref_table WHERE col_1 = -78;
-COPY mx_ref_table (col_1, col_2) FROM STDIN WITH (FORMAT 'csv');
-SELECT * FROM mx_ref_table ORDER BY col_1;
-
 \c - - - :master_port
 DROP TABLE mx_ref_table;
 CREATE UNIQUE INDEX mx_test_uniq_index ON mx_table(col_1);