Index: Source/Entities/EntityData.cst
===================================================================
--- Source/Entities/EntityData.cst	(revision 559)
+++ Source/Entities/EntityData.cst	(working copy)
@@ -30,7 +30,7 @@
 	/// </remarks>
 	[EditorBrowsable(EditorBrowsableState.Never)]
 	[Serializable]
-	internal protected class <%=structName%> : ICloneable
+	internal protected class <%=structName%> : ICloneable, ICloneableEx
 	{
 		#region Variable Declarations
 		private EntityState currentEntityState = EntityState.Added;
@@ -191,6 +191,81 @@
 			return _tmp;
 		}
 		
+		/// <summary>
+		/// Creates a new object that is a copy of the current instance.
+		/// </summary>
+		/// <returns>A new object that is a copy of this instance.</returns>
+		public object Clone(IDictionary existingCopies)
+		{
+			if (existingCopies == null)
+				existingCopies = new Hashtable();
+				
+			<%=structName%> _tmp = new <%=structName%>();
+						
+			<% for(int i=0; i<SourceTable.PrimaryKey.MemberColumns.Count; i++) { %>
+			_tmp.<%=GetPropertyName(SourceTable.PrimaryKey.MemberColumns[i])%> = this.<%=GetPropertyName(SourceTable.PrimaryKey.MemberColumns[i])%>;
+			<% if (!IsIdentityColumn(SourceTable.PrimaryKey.MemberColumns[i]) && !(IsComputed(SourceTable.PrimaryKey.MemberColumns[i]))) {%>
+			_tmp.<%=GetOriginalPropertyName(SourceTable.PrimaryKey.MemberColumns[i])%> = this.<%=GetOriginalPropertyName(SourceTable.PrimaryKey.MemberColumns[i])%>;
+			<% } %>
+			<% } %>
+			
+			<% for (int x=0; x < SourceTable.NonPrimaryKeyColumns.Count; x++) { %>
+			_tmp.<%= GetPropertyName(SourceTable.NonPrimaryKeyColumns[x]) %> = this.<%= GetPropertyName(SourceTable.NonPrimaryKeyColumns[x]) %>;
+			<% } %>
+			
+			#region Source Parent Composite Entities
+			<% if (IncludeGetListByFK) { %>
+			<%	//Generate a Source property for each foreign key relation
+				System.Collections.ArrayList filled = new System.Collections.ArrayList();
+				foreach(TableKeySchema tableKey in SourceTable.ForeignKeys)
+				{	
+					// related table must be in the selection
+					if (SourceTables.Contains(tableKey.PrimaryKeyTable)) {
+					string fkPropertyName = GetKeysName(tableKey.ForeignKeyMemberColumns);
+					
+					if(filled.Contains(fkPropertyName))
+						continue;
+						
+					filled.Add(fkPropertyName);
+					
+				string pkClassName = GetClassName(tableKey.PrimaryKeyTable.Name);
+					
+				%>
+			if (this.<%=fkPropertyName%>Source != null && existingCopies.Contains(this.<%=fkPropertyName%>Source))
+				_tmp.<%=fkPropertyName%>Source = existingCopies[this.<%=fkPropertyName%>Source] as <%= pkClassName %>;
+			else
+				_tmp.<%=fkPropertyName%>Source = MakeCopyOf(this.<%=fkPropertyName%>Source, existingCopies) as <%= pkClassName %>;
+				<%	} //end if in SourceTables
+				} //end for each FK
+		  	}// IncludeGetListByFK%>	
+			#endregion
+		
+			#region Child Collections
+			<% if (IncludeRelations){
+			int ctr = 0;
+			foreach(CollectionInfo item in GetChildrenCollections(SourceTable, SourceTables).Values) { 
+				if (ctr == 0)
+					Response.Write("\t\t\t//deep copy nested objects" + Environment.NewLine);
+				ctr++;
+				
+				string typeName = "";
+				if (item.CollectionRelationshipType == MoM.Templates.CommonSqlCode.RelationshipType.OneToOne)
+					typeName = item.TypeName;
+				else
+					typeName = item.CollectionTypeName;
+			%>
+			_tmp.<%= item.PropertyNameUnique %> = (<%= typeName %>) MakeCopyOf(this.<%=item.PropertyNameUnique %>, existingCopies); 
+				<% }//end foreach CollectionInfo
+			}//end if IncludeRelations
+			%>
+			#endregion Child Collections
+			
+			//EntityState
+			_tmp.EntityState = this.EntityState;
+			
+			return _tmp;
+		}
+		
 		#endregion Clone Method
 		
 		/// <summary>
@@ -362,3 +437,4 @@
 }
 </script>
 
+
Index: Source/Entities/EntityInstanceBase.generated.cst
===================================================================
--- Source/Entities/EntityInstanceBase.generated.cst	(revision 559)
+++ Source/Entities/EntityInstanceBase.generated.cst	(working copy)
@@ -91,7 +91,7 @@
 	<% } %>
 	[Serializable, DataObject]
 	[CLSCompliant(true)]
-	public abstract partial class <%=abstractClassName%> : EntityBase, <%=NameSpace%>.I<%= className %>, IEntityId<<%= keyClassName %>>, System.IComparable, System.ICloneable, IEditableObject, IComponent, INotifyPropertyChanged
+	public abstract partial class <%=abstractClassName%> : EntityBase, <%=NameSpace%>.I<%= className %>, IEntityId<<%= keyClassName %>>, System.IComparable, System.ICloneable, ICloneableEx, IEditableObject, IComponent, INotifyPropertyChanged
 	{		
 		#region Variable Declarations
 		
@@ -513,37 +513,47 @@
 		///<summary>
 		///  Returns a Typed <%=className%> Entity 
 		///</summary>
-		public virtual <%=className%> Copy()
+		protected virtual <%=className%> Copy(IDictionary existingCopies)
 		{
+			if (existingCopies == null)
+			{
+				// This is the root of the tree to be copied!
+				existingCopies = new Hashtable();
+			}
+
 			//shallow copy entity
 			<%=className%> copy = new <%=className%>();
+			existingCopies.Add(this, copy);
 			copy.SuppressEntityEvents = true;
 			<% for (int x=0; x < cols.Count; x++) { %>
-			copy.<%= GetPropertyName(cols[x]) %> = this.<%= GetPropertyName(cols[x]) %>;
-			<% if( cols[x].IsPrimaryKeyMember && !IsIdentityColumn(cols[x]) && !IsComputed(cols[x]) ) { %>
-			copy.<%= GetOriginalPropertyName(cols[x]) %> = this.<%= GetOriginalPropertyName(cols[x]) %>;
+				copy.<%= GetPropertyName(cols[x]) %> = this.<%= GetPropertyName(cols[x]) %>;
+				<% if( cols[x].IsPrimaryKeyMember && !IsIdentityColumn(cols[x]) && !IsComputed(cols[x]) ) { %>
+					copy.<%= GetOriginalPropertyName(cols[x]) %> = this.<%= GetOriginalPropertyName(cols[x]) %>;
+				<% } %>
 			<% } %>
-			<% } %>
 			
 			<% if (IncludeGetListByFK) { %>
-			<%	//Generate a Source property for each foreign key relation
-			System.Collections.ArrayList filled = new System.Collections.ArrayList();
-			foreach(TableKeySchema tableKey in SourceTable.ForeignKeys)
-			{	
-				// related table must be in the selection
-				if (SourceTables.Contains(tableKey.PrimaryKeyTable)) {
-				string fkPropertyName = GetKeysName(tableKey.ForeignKeyMemberColumns);
+				<%	//Generate a Source property for each foreign key relation
+				System.Collections.ArrayList filled = new System.Collections.ArrayList();
+				foreach(TableKeySchema tableKey in SourceTable.ForeignKeys)
+				{	
+					// related table must be in the selection
+					if (SourceTables.Contains(tableKey.PrimaryKeyTable)) {
+						string fkPropertyName = GetKeysName(tableKey.ForeignKeyMemberColumns);
 				
-				if(filled.Contains(fkPropertyName))
-					continue;
+						if(filled.Contains(fkPropertyName))
+							continue;
+						
+						filled.Add(fkPropertyName);
 					
-				filled.Add(fkPropertyName);
-				
-				string pkClassName = GetClassName(tableKey.PrimaryKeyTable.Name);
-			%>
-			copy.<%=fkPropertyName%>Source = MakeCopyOf(this.<%=fkPropertyName%>Source) as <%= pkClassName %>;
-			<%	} //end if in SourceTables
-			} //end for each FK
+						string pkClassName = GetClassName(tableKey.PrimaryKeyTable.Name);
+						%>
+			if (this.<%=fkPropertyName%>Source != null && existingCopies.Contains(this.<%=fkPropertyName%>Source))
+				copy.<%=fkPropertyName%>Source = existingCopies[this.<%=fkPropertyName%>Source] as <%= pkClassName %>;
+			else
+				copy.<%=fkPropertyName%>Source = MakeCopyOf(this.<%=fkPropertyName%>Source, existingCopies) as <%= pkClassName %>;
+			<%		} //end if in SourceTables
+				} //end for each FK
 		  }// IncludeGetListByFK%>	
 		
 		<% 
@@ -560,13 +570,23 @@
 			else
 				typeName = item.CollectionTypeName;
 		%>
-			copy.<%= item.PropertyNameUnique %> = (<%= typeName %>) MakeCopyOf(this.<%=item.PropertyNameUnique %>); 
+			copy.<%= item.PropertyNameUnique %> = (<%= typeName %>) MakeCopyOf(this.<%=item.PropertyNameUnique %>, existingCopies); 
 			<% }//end foreach CollectionInfo
 		}//end if IncludeRelations
 		%>
 			copy.EntityState = this.EntityState;
 			copy.SuppressEntityEvents = false;
 			return copy;
+		}		
+		
+		
+		
+		///<summary>
+		///  Returns a Typed <%=className%> Entity 
+		///</summary>
+		public virtual <%=className%> Copy()
+		{
+			return this.Copy(null);	
 		}
 		
 		///<summary>
@@ -574,10 +594,18 @@
 		///</summary>
 		public object Clone()
 		{
-			return this.Copy();
+			return this.Copy(null);
 		}
 		
 		///<summary>
+		/// ICloneableEx.Clone() Member, returns the Shallow Copy of this entity.
+		///</summary>
+		public object Clone(IDictionary existingCopies)
+		{
+			return this.Copy(existingCopies);
+		}
+		
+		///<summary>
 		/// Returns a deep copy of the child collection object passed in.
 		///</summary>
 		public static object MakeCopyOf(object x)
@@ -595,6 +623,29 @@
 		}
 		
 		///<summary>
+		/// Returns a deep copy of the child collection object passed in.
+		///</summary>
+		public static object MakeCopyOf(object x, IDictionary existingCopies)
+		{
+			if (x == null)
+				return null;
+			
+			if (x is ICloneableEx)
+			{
+				// Return a deep copy of the object
+				return ((ICloneableEx)x).Clone(existingCopies);
+			}
+			else if (x is ICloneable)
+			{
+				// Return a deep copy of the object
+				return ((ICloneable)x).Clone();
+			}
+			else
+				throw new System.NotSupportedException("Object Does Not Implement the ICloneable or IClonableEx Interface.");
+		}
+		
+		
+		///<summary>
 		///  Returns a Typed <%=className%> Entity which is a deep copy of the current entity.
 		///</summary>
 		public virtual <%=className%> DeepCopy()
@@ -679,10 +730,11 @@
         ///<returns>true if Object1 is a <see cref="<%=abstractClassName%>"/> and has the same value as this instance; otherwise, false.</returns>
         public override bool Equals(object Object1)
         {
-			if (Object1 is <%=abstractClassName%>)
-				return Equals(this, (<%=abstractClassName%>)Object1);
-			else
+			// Cast exception if Object1 is null or DbNull
+			if (Object1 == null || Object1 == DBNull.Value)
 				return false;
+			else	
+            			return Equals(this, (<%=abstractClassName%>)Object1);
         }
 
         /// <summary>
Index: Source/Entities/IEntity.cst
===================================================================
--- Source/Entities/IEntity.cst	(revision 559)
+++ Source/Entities/IEntity.cst	(working copy)
@@ -20,6 +20,7 @@
 %>
 using System;
 using System.ComponentModel;
+using System.Collections;
 
 namespace <%=NameSpace%>
 {
@@ -140,4 +141,17 @@
 		///</summary>
 		string EntityTrackingKey {	get;  set;  }
 	}
+	
+	/// <summary>
+	///     Interface that TList and every entity implements to support
+	///		cloning of an object tree.
+	/// </summary>
+	public interface ICloneableEx
+	{
+		///<summary>
+		/// The tracking key used to with the <see cref="EntityLocator" />
+		///</summary>
+		///<param name="existingCopies">A list containing references to all objects already copied.</param>
+		object Clone(IDictionary existingCopies);
+	}
 }
Index: Source/Entities/ListBase.cst
===================================================================
--- Source/Entities/ListBase.cst	(revision 559)
+++ Source/Entities/ListBase.cst	(working copy)
@@ -26,7 +26,7 @@
    /// Supports filtering, databinding, searching and sorting.
    /// </summary>
    [Serializable]
-   public abstract class ListBase<T> : BindingList<T>, IBindingListView, IBindingList, IList, ICloneable, IListSource, ITypedList, IDisposable, IComponent, IRaiseItemChangedEvents, IDeserializationCallback
+   public abstract class ListBase<T> : BindingList<T>, IBindingListView, IBindingList, IList, ICloneable, ICloneableEx, IListSource, ITypedList, IDisposable, IComponent, IRaiseItemChangedEvents, IDeserializationCallback
    {
       private List<T> _OriginalList = new List<T>();
 
@@ -578,6 +578,15 @@
       }
 
       ///<summary>
+      /// Creates an exact copy of this instance.
+      ///</summary>
+      ///<implements><see cref="ICloneableEx.Clone"/></implements>
+	  public virtual object Clone(IDictionary existingCopies)
+      {
+         throw new NotImplementedException("Method not implemented.");
+      }
+		
+      ///<summary>
       /// Creates an exact copy of this TList{T} object.
       ///</summary>
       ///<returns>A new, identical copy of the TList{T} casted as object.</returns>
@@ -594,7 +603,31 @@
                 System.NotSupportedException("object not cloneable");
          }
       }
-      #endregion ICloneable
+
+	      ///<summary>
+      /// Creates an exact copy of this TList{T} object.
+      ///</summary>
+      ///<returns>A new, identical copy of the TList{T} casted as object.</returns>
+      public static object MakeCopyOf(object x, IDictionary existingCopies)
+      {
+		 if (x is ICloneableEx)
+		 {
+            // Return a deep copy of the object
+            return ((ICloneableEx)x).Clone(existingCopies);
+		 }
+         else if (x is ICloneable)
+         {
+            // Return a deep copy of the object
+            return ((ICloneable)x).Clone();
+         }
+         else
+         {
+            throw new
+                System.NotSupportedException("object not cloneable");
+         }
+      }
+	
+	  #endregion ICloneable
 	  
 	  #region PropertyCollection
 	  /// <summary>
Index: Source/Entities/TList.cst
===================================================================
--- Source/Entities/TList.cst	(revision 559)
+++ Source/Entities/TList.cst	(working copy)
@@ -119,8 +119,18 @@
 		///<implements><see cref="ICloneable.Clone"/></implements>
 		public override object Clone()
 		{
-			return this.Copy();
+			return this.Copy(null);
 		}
+		
+		///<summary>
+		/// Creates an exact copy of this TList{T} instance.
+		///</summary>
+		///<returns>The TList{T} object this method creates, cast as an object.</returns>
+		///<implements><see cref="ICloneableEx.Clone"/></implements>
+		public override object Clone(IDictionary existingCopies)
+		{
+			return this.Copy(existingCopies);
+		}
 	
 		///<summary>
 		/// Creates an exact copy of this TList{T} object.
@@ -128,10 +138,26 @@
 		///<returns>A new, identical copy of the TList{T}.</returns>
 		public virtual TList<T> Copy()
 		{
+			return this.Copy(null);
+		}
+	
+		///<summary>
+		/// Creates an exact copy of this TList{T} object.
+		///</summary>
+		///<returns>A new, identical copy of the TList{T}.</returns>
+		public virtual TList<T> Copy(IDictionary existingCopies)
+		{
+			if (existingCopies == null)
+				existingCopies = new Hashtable();
+				
 			TList<T> copy = new TList<T>();
 			foreach (T item in this)
 			{
-				T itemCopy = (T)MakeCopyOf(item);
+				T itemCopy = default(T);
+				if (existingCopies.Contains(item))
+					itemCopy = (T)existingCopies[item];
+				else
+					itemCopy = (T)MakeCopyOf(item, existingCopies);
 				copy.Add(itemCopy);
 			}