would this sour the short Sale? Lets say the SS is pending and i start marketing the property. Once the ss is approved could I call the lender and tell them I have someone that is going to close on the property on the closing day? Then use a contract agreement with my end buy to collect my assignment fee?
You can’t do that.
Lenders won’t allow it, and they specifically state WHO the payoff is to come from in most cases. Just do a double closing. It will cost you a few extra bucks, but you can get the deal done. In my experience, you can’t assign short sale contracts (even when they say you can, as mine does) The payoff letter will state it is not assignable.