Well first if you have ratified a contract on a short sale home. Congratulations!
If so I would recommend that you ask your Realtor all the questions you have about the short sale process.
However, for the interest of all those who read these posts, it's a great question.
The role of the negotiator ( also known as the Loss Specialist ) is to gather all the paperwork necessary to submit the file to the investors for short sale approval. This means from all parties. The seller,the listing agent, the buyers agent as well as the title company. The title company willl be required to submit a preliminary Hud-1 to show the bank how much your offer will net the bank.
The short sale process is very much like the Buying Process only backwards!