Soi got THIS message on Facebook messenger from my mother-in-laws sister earlier: So, what have you decided to do with your new last name once you're married? What would y'all do. I deleted the message and did NOT respond. I mentioned it to my MIL who told me not to worry about it. I told her that's really NONE of her sister's business. Yes I'm a little upset about it. I get this is his first marriage and my third, but I'm not marrying her child.