I do not address any such Mr. and Mrs. at all. I have a family that is all messed up. What they get is their first name and last: Jane and john doe. That is it. Singles, just to the family member only, and not the one shacking up with them. Our daughter get her name and addressed to her and not the other guy. He is not recognized. Even my mother, it is her name and the other man's name who wed civally. No Mr. and Mrs. and they get no anniversary cards either. Oh well, that is what they want and that is it, with prayers for your peace.