Princess Daisy Boo, thanks for sharing your story. I agree that my sister should just do whatever will make her and her intended happiest, but unfortunately, our mother's behavior is casting a pall on what should be a happy event. It makes me really upset for my sister.
Atlantis, thanks for the screen print.
It sounds as though my mother has doctrinal support for being a jackass over this matter, unfortunately. If anyone can think of a way to doctrinally support that my mother should attend (or is not prohibited from attending), it would be really helpful. Maybe I should just tell her that I posted the situation on a board filled with ex-JWs and they all support her not attending my sister's wedding. I'm sure she'll be happy that the apostate community agrees with her decision making, LOL.
Thanks again everyone.
ETA: Oompa, jgnat and mustang all posted while I was typing. Thanks for the food for thought. I really appreciate your all taking the time to respond.