Basically my SIL can be very rude and my MIL is an enabler. MIL is a completely different person without SIL around, but I can never invite my MIL anywhere, she always brings SIL(22, still lives at home) even if she's not invited. So if I invite one I'm getting both. My SIL can be very jealous. She says I stole her brother and thinks I'm trying to steal her place in the family. I'm worried that if I invite my MIL that my SIL will come, act curt and again say I'm trying to be her and that I'm taking away her experience (she thinks she should be the first or only one to have any mother/daughter moments.) MIL coddles her when she acts this way and says I need to be understanding of her feelings no matter what SIL says to me or does. I think it would ruin my dress shopping experience.
Do I have to invite my MIL? Is there some way to invite just MIL excluding my SIL without hurting SIL feelings? Is there a way to prevent attitude from SIL if she comes?