Agree with Ricks refresh question
Also please be careful with your terminology. Based on what you've described the workitem is not being Forwarded, but the 1st workitem is being completed with the 'obsolete' outcome and a new workitem is being created.
In MSS is it the UWL you are talking about or something like a POWL work list. I can imagine that a POWL might show the Leave request as outstanding but not actually be based on the WF (this is just a guess).
Does the MSS inbox actually show WF workitems?
Have fun,
Mark