Hey guys, I know this post is really old, but its one of the only websites with this question, so I had to post the solution I found for others to see. If I had this problem, then im sure others have had it, too. (Of course this program probably wasnt around then, but still.) There is this amazing, free program called OnTopReplica that does exactly what (I think) you are talking about. Its simple and works. Here is the link: http://ontopreplica.codeplex.com/

Hope this helps people looking for a good solution.