It's a strange situation, but my FI is very close to his ex-brother-in-law. He has no brothers and has never been close to his sister. His sister and BIL were together for about 15 years and the family had adopted him as their own since his parents are both deceased. Now they've been divorced for about two years but my FI's bond with BIL hasn't changed.Now he's asked his BIL to be in our bridal party. Being that he's not close to his sis and I have a solid group of BM's, he didn't think to have her as one. His normally easy going parents are threatening not to come if BIL is in and sister is not. What to do??