I agree with all parts of the previous answer, except the second sentence. Judging by the very good and clear advice Christopher offered, perhaps he mis-typed.
Technically, "Ratification" is when all parties to the contract (the owner and you) sign all documents, and all parties have a copy of that contract. One of the docs is likely a SHORT SALE addendum, or something which makes the thrid party approval a contingency. However, as Christopher said, the bank(s) are not party to the contract.
I hope you have an agent - ESPECIALLY with this type of transaction, you should have someone experienced with these types of transactions to explain each step and the risks and benefits involved (both of which are significant IF you have experienced agent representing YOU).
As for your lender, talk to your loan officer. Banks have varying policies on their lock - some allow you to re-lock, some offer extended locks, etc. etc. Hopefully you've chosen a lender who has a great amount of integrity, understands how these shorts sales can drag on and is someone who will be your advocate. If not, then think again. I have some great lenders I can recommend (see the Service Provider page of my web site). One in particular, Cindy Fox with SunTrust, stands out as a tremendous advocate for the buyer - she impresses me at every turn. If you're not comfortable with the loan officer you've chosen, please call her. You can trust every word she says - she's the kind of person who really does look to earn your business for life by guiding you through the lending process to ensure you have the best loan available to you, and she'll help you understand when to lock and when to wait in order to avoid unnecessary costs.
Short sale approvals can take way longer than they should - hang on - it's gonna be a bumpy ride.