Index: lams_tool_forum/conf/hibernate/mappings/org/lamsfoundation/lams/tool/forum/persistence/Message.hbm.xml
===================================================================
diff -u -r2dbea686e81e6a5843328d8c0bd814b63e64d36f -r4927ee743a679c87a515436a0cc289b8bbc84ccd
--- lams_tool_forum/conf/hibernate/mappings/org/lamsfoundation/lams/tool/forum/persistence/Message.hbm.xml	(.../Message.hbm.xml)	(revision 2dbea686e81e6a5843328d8c0bd814b63e64d36f)
+++ lams_tool_forum/conf/hibernate/mappings/org/lamsfoundation/lams/tool/forum/persistence/Message.hbm.xml	(.../Message.hbm.xml)	(revision 4927ee743a679c87a515436a0cc289b8bbc84ccd)
@@ -189,7 +189,7 @@
             name="sessionClones"
             lazy="false"
             inverse="false"
-            cascade="all-delete-orphan"
+            cascade="none"
             sort="unsorted"
         >
 
Index: lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/persistence/Message.java
===================================================================
diff -u -r2dbea686e81e6a5843328d8c0bd814b63e64d36f -r4927ee743a679c87a515436a0cc289b8bbc84ccd
--- lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/persistence/Message.java	(.../Message.java)	(revision 2dbea686e81e6a5843328d8c0bd814b63e64d36f)
+++ lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/persistence/Message.java	(.../Message.java)	(revision 4927ee743a679c87a515436a0cc289b8bbc84ccd)
@@ -497,7 +497,7 @@
     /**
      * @return the set of all messages cloned from this message. See getAuthoredParent().
      * 
-     * @hibernate.set cascade="all-delete-orphan" inverse="false"
+     * @hibernate.set cascade="none" inverse="false"
      * @hibernate.collection-key column="authored_parent_uid"
      * @hibernate.collection-one-to-many class="org.lamsfoundation.lams.tool.forum.persistence.Message"
      * 
Index: lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/service/ForumService.java
===================================================================
diff -u -r1ef4b877aea0883709c641351e07595c6be84361 -r4927ee743a679c87a515436a0cc289b8bbc84ccd
--- lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/service/ForumService.java	(.../ForumService.java)	(revision 1ef4b877aea0883709c641351e07595c6be84361)
+++ lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/service/ForumService.java	(.../ForumService.java)	(revision 4927ee743a679c87a515436a0cc289b8bbc84ccd)
@@ -300,15 +300,23 @@
     }
 
     public void deleteTopic(Long topicUid) throws PersistenceException {
-	List children = messageDao.getChildrenTopics(topicUid);
+	Message topic = messageDao.getById(topicUid);
+	
 	// cascade delete children topic by recursive
+	List children = messageDao.getChildrenTopics(topicUid);
 	if (children != null) {
 	    Iterator iter = children.iterator();
 	    while (iter.hasNext()) {
 		Message msg = (Message) iter.next();
 		this.deleteTopic(msg.getUid());
 	    }
 	}
+	
+	// recursively delete clones
+	for (Message clone : (Set<Message>) topic.getSessionClones()) {
+	    this.deleteTopic(clone.getUid());
+	}
+	
 	messageSeqDao.deleteByTopicId(topicUid);
 	messageDao.delete(topicUid);
     }
@@ -708,7 +716,6 @@
 	}
 
 	Forum toContent = Forum.newInstance(fromContent, toContentId, forumToolContentHandler);
-	forumDao.saveOrUpdate(toContent);
 
 	// save topics in this forum, only save the author created topic!!! and reset its reply number to zero.
 	Set topics = toContent.getMessages();
@@ -729,6 +736,8 @@
 		createRootTopic(toContent.getUid(), (ForumToolSession) null, msg);
 	    }
 	}
+	
+	forumDao.saveOrUpdate(toContent);
 
     }