My wife and mother-in-law own a condo in Palm Beach County, FL... JTWROS. My mother-in-law passed away in MA and the also the condo is in my wife's maiden name. What has to be done to transfer the deed to our married name and also add my name to the deed?

Your wife has to prepare a deed from herself, as Seller, to the two of you, as Buyers. The Seller portion should have her maiden name and married name (e.g. Jane Doe Smith). The Buyer portion can list just her married name. Then the deed has to be recorded in the county clerk or county register's office.

I suggest that you have a title company or attorney prepare this for you. It shouldn't be expensive and you'll know that it was done properly. If you do it yourself and make a mistake it can be costly to fix.