I have a BM who doesn't quite seem to grasp the concept of measurements, and bought a dress that was far, far too small for her. She thinks it looks great and said that, "tight is in right now," but there's a difference between tight and obscene. She can't zip the dress, but said she'll just get it switched to have a corset back or pin it. Is it acceptable to tell her that I understand the confusion between street sizes and BM dress sizes, but that I don't want her wearing a dress in my wedding that clearly doesn't fit? How should I go about telling her that she needs to buy a bigger size? Thanks!
P.S. I'm sorry if this is rude, but the dress is actually obscene with how tight it is and how much it shows.