A short sale offer will touch many hands from a processor, negotiator, asset manager, etc. Essentially, these are middle men to the investor. The investor will make the final call as to what they will accept and reject in terms of your offer.
A BPO is not an appraisal but a Broker Price Opinion on what they believe the house will sell for under certain conditions in the current market as a distressed and standard sale utilizing recent sales of homes nearby .
if your short sale is moving along quickly and your getting response things are going well. if the BPO came back at 178k anticipate a counter offer from the bank.