Is too much risk and expenses to do so. The best solution in my opinion will be pospone the closing until the sellers are ready to move out and keep on with their life in another property.
Best of Luck,
The tough part is that you really don't know for sure until the seller's listing agent gets back the final short sale approval documents. You can have your Realtor check with the listing agent to see if he/she has an idea of the lender's policy.
As for your concern about property damage, it's quite valid. You do expose yourself to potential damage with a short sale rent back. The best solution is to treat the rent back just like any other lease. Have a walk-through with the seller and hold a security deposit. Postponing the close, while it's a good idea and works for regular sales, doesn't work on short sales. The short sale approval documents often have strict closing deadlines that must be met in order for the short sale to complete.