I say give it to the sister. If she doesn't like it, will she tell you? If so, tell her to regift it to someone in her new husbands family who greatly admires it...hopefully, her new mother-in-law! Your (possibly) MIL will probably never know what your sister does with the quilt. Just tell her what a beautiful job she did, give her a little more money than she charged you and get on with your life! Good luck.