I answered some questions about SS but I can not find them in my list quickly. You may check my Q&A.
When I answer real estate question, I always focus on legal and ethical aspects.
Remember lender's role in SS transaction. Lender's decision is the contingency not the whole contract. How to deal the contract is still a negotiation between buy and seller. Lender can only say as yes, I approve the price or no, I donot. Maybe, lender can even have no responses. Law doesnot say that lender must answer yes or no in a specific period. You can think about how buyer's lender works in a transaction. That is similar.
Here, I would like to mention two things. First, real estate is a statewide business but loan is a nationwide. Second, most lenders which have a lot trouble borrowers, have no legal department or no strong legal knowledge to understand all the states which their loan business cover. That is not hard to believe that lenders are easy to break or ignore the local real state laws. Especially in CA called legal and real estate pioneer state, outside lenders always do something that they believe they are right but in CA, they are wrong.
Also, since end of 2008, the laws and regulations keep changing. Some lenders may have no time to update their understanding. By the way, otherwise, they would not have today's trouble. When lender tells or yells you to do this or that, do be afraid. The lender may not be right.