diff --git a/sfdx-source/apex-common/main/classes/fflib_SObjectUnitOfWork.cls b/sfdx-source/apex-common/main/classes/fflib_SObjectUnitOfWork.cls
index 537bf3ed78..b3f15bf8df 100644
--- a/sfdx-source/apex-common/main/classes/fflib_SObjectUnitOfWork.cls
+++ b/sfdx-source/apex-common/main/classes/fflib_SObjectUnitOfWork.cls
@@ -707,6 +707,7 @@ public virtual class fflib_SObjectUnitOfWork
 	{
 		for (Schema.SObjectType sObjectType : m_sObjectTypes)
 		{
+            m_relationships.get(sObjectType.getDescribe().getName()).resolve();
 			m_dml.dmlUpdate(m_dirtyMapByType.get(sObjectType.getDescribe().getName()).values());
 		}
 	}
@@ -809,12 +810,11 @@ public virtual class fflib_SObjectUnitOfWork
         public void resolve()
         {
             // Resolve relationships
-            for (IRelationship relationship : m_relationships)
-            {
-                //relationship.Record.put(relationship.RelatedToField, relationship.RelatedTo.Id);
-                relationship.resolve();
-            }
-
+            for (Integer i = (m_relationships.size() - 1); i >= 0; i--) {
+                if (m_relationships.get(i).resolve()) {
+                    m_relationships.remove(i);
+                }
+            } 
         }
 
         public void add(SObject record, Schema.SObjectField relatedToField, Schema.SObjectField externalIdField, Object externalId)
@@ -874,7 +874,7 @@ public virtual class fflib_SObjectUnitOfWork
 
     private interface IRelationship
     {
-        void resolve();
+        Boolean resolve();
     }
 
     private class RelationshipByExternalId implements IRelationship
@@ -886,11 +886,16 @@ public virtual class fflib_SObjectUnitOfWork
         public Schema.SObjectField ExternalIdField;
         public Object ExternalId;
 
-        public void resolve()
+        public Boolean resolve()
         {
+            if (ExternalId == null) {
+                return false;
+            }
+
             SObject relationshipObject = this.RelatedTo.newSObject();
             relationshipObject.put( ExternalIdField.getDescribe().getName(), this.ExternalId );
             this.Record.putSObject( this.RelationshipName, relationshipObject );
+            return true;
         }
     }
 
@@ -900,9 +905,14 @@ public virtual class fflib_SObjectUnitOfWork
         public Schema.SObjectField RelatedToField;
         public SObject RelatedTo;
 
-        public void resolve()
+        public Boolean resolve()
         {
+            if (String.isBlank(this.relatedTo.Id)) {
+                return false;
+            }
+
             this.Record.put( this.RelatedToField, this.RelatedTo.Id);
+            return true;
         }
     }
 
@@ -911,9 +921,14 @@ public virtual class fflib_SObjectUnitOfWork
         public Messaging.SingleEmailMessage email;
         public SObject relatedTo;
 
-        public void resolve()
+        public Boolean resolve()
         {
+            if (String.isBlank(this.relatedTo.Id)) {
+                return false;
+            }
+
             this.email.setWhatId( this.relatedTo.Id );
+            return true;
         }
     }
 
diff --git a/sfdx-source/apex-common/test/classes/fflib_SObjectUnitOfWorkTest.cls b/sfdx-source/apex-common/test/classes/fflib_SObjectUnitOfWorkTest.cls
index 582e759bc3..e4f8ab2c05 100644
--- a/sfdx-source/apex-common/test/classes/fflib_SObjectUnitOfWorkTest.cls
+++ b/sfdx-source/apex-common/test/classes/fflib_SObjectUnitOfWorkTest.cls
@@ -608,6 +608,63 @@ private with sharing class fflib_SObjectUnitOfWorkTest
         );
     }
 
+    @IsTest
+    private static void testRegisterDirtyWithRelationship() {
+        // GIVEN an existing opportunity
+        Opportunity existingOpp = new Opportunity(
+            Id = fflib_IDGenerator.generate(Schema.Opportunity.SObjectType),
+            Name = 'Existing Opportunity',
+            StageName = 'Closed',
+            CloseDate = System.today()
+        );
+        // AND an existing Account to which the existing opportunity will be related to
+        Account newAccount = new Account(
+            Name = 'New Account'
+        );
+
+        // WHEN
+        Test.startTest();
+        MockDML mockDML = new MockDML();
+        List<Schema.SObjectType> mySobjects = new List<Schema.SObjectType>{
+            Opportunity.SObjectType,
+            Account.SObjectType
+        };
+        fflib_SObjectUnitOfWork uow = new fflib_SObjectUnitOfWork(mySobjects, mockDML);
+        uow.registerNew(newAccount);
+        uow.registerDirty(existingOpp, Opportunity.AccountId, newAccount);
+        uow.commitWork();
+        Test.stopTest();
+
+        // THEN
+        System.Assert.isTrue(
+            new fflib_MatcherDefinitions.SObjectsWith(
+                new List<Map<SObjectField, Object>>{
+                    new Map<SObjectField, Object>
+                    {
+                        Account.Id => newAccount.Id,
+                        Account.Name => 'New Account'
+                    }
+                }
+            ).matches(mockDML.recordsForInsert),
+            'The new account record does not match'
+        );
+
+        // AND
+        System.Assert.isTrue(
+            new fflib_MatcherDefinitions.SObjectsWith(
+                new List<Map<SObjectField, Object>>{
+                    new Map<SObjectField, Object>
+                    {
+                        Opportunity.Id => existingOpp.Id,
+                        Opportunity.Name => 'Existing Opportunity',
+                        Opportunity.StageName => 'Closed',
+                        Opportunity.AccountId => newAccount.Id
+                    }
+                }
+            ).matches(mockDML.recordsForUpdate),
+            'The opportunity record should be related to the new Account'
+        );
+    }
     @IsTest
     private static void testRegisterUpsert() {
         Opportunity existingOpp = new Opportunity(
@@ -824,6 +881,12 @@ private with sharing class fflib_SObjectUnitOfWorkTest
 
         public void dmlInsert(List<SObject> objList)
         {
+            for (SObject obj : objList) {
+                if (obj == null) {
+                    continue;
+                }
+                obj.Id = fflib_IDGenerator.generate(obj.getSObjectType());
+            }
             this.recordsForInsert.addAll(objList);
         }