First the seller needs to be 100% motivated to go forward with the short sale process. This means that the seller has explored all other options for example loan modification etc and have came to a conclusion that short sale is the most viable option to deal with the hardship that the seller faces. Second most important link in this chain is having a strong agent who not only is experienced in dealing with short sales but also knows and understands how to deal with the investor. The third link in this chain is the investor who is the note holder on your mortgages. Your listing agent will collect all the documents from you and send it to the lender. Depending on who the lender is, your file will be assigned a negotiator, who will also be the point of contact for you and your listing agent. All the communication including submitting an offer, will be done with this negotiator. The negotiator will then present your offer internally to senior management and/or investor. Based on this review and a Broker price opinion on your property, present value if your home will be determined and if the offer your agent has presented to the negotiator is close to the BPO value then a Short Sale approval will be granted. On the other hand, if the offer is considerable lower then the boo value, a counter offer will be made. So, to answer your question, the seller, agent and investor has the most control over the short sale process.