I'm in quite a pickle.
My fiance and I got engaged last October. At the time, we decided we wanted a small wedding party (3 on each side). FH's sister majored in music in college and has been playing piano since she was young... she is a beautiful piano player. Instead of asking her to be a bridesmaid, we asked her to be our pianist.
Fast forward nearly 10 months later. My future M-I-L tells me and the fiance that his sister has been very upset that she's not in the bridal party. Of course, the sister has never said a word to us about it, and I feel terrible that she wants to be a bridesmaid. At this point, it's awkward because if we would ask her to be a bridesmaid, she'd think it was just out of pity or because we found out she wanted to be in the wedding. I really want her to be our pianist; the fiance doesn't care either way. He's backpeddling at this point, saying that it's tradition for all siblings to be in the party. One of my siblings is in the wedding, the other two are not.
I really don't know how to please everybody. I'm happy with blissfully ignoring that she wants in the bridal party--quite frankly, I feel that my M-I-L never should have told me. But I don't want my fiance's sister to look back on our wedding with resentment because she wasn't in the bridal party. Thoughts?