My future sister-in-law has expressed several times that she wants to sing for our wedding. The problem is, we've been family friends with my in-laws for years, and I can't think of a single graduation party, superbowl, or any get-together where she hasn't stopped the festivities and put on a performance for all the attendees. It may sound selfish, but for my wedding, I just kind of want that one day to not be her performance. She has a lovely voice, and is pursuing musical theatre as a profession, so these "impromptu" performances are taken very seriously, and I know from past experience with her and my mother-in-law that me being the one to botch the idea would be taken very offensively. Luckily, the church is very strict on using only their hired vocalists, but I am still concerned about the reception. I have included her already as a bridesmaid, and I think she should be happy with that role. How can I make sure she doesn't sing without causing a huge amount of drama? My fiance doesn't understand why I would have a problem with it, so he may not be much help.
(I know this may come across as petty, but my future sister-in-law has a tendency to want all eyes on her. She even announced my engagement on facebook before I could tell my own relatives.... Is is so bad for the bride to want to avoid others getting so much attention on her wedding day?) Please help!