Ok so my sister and her ex are not really friends. They say hi to each others but that's it.However he is a great friend to me and my other brothers and sisters as he was once apart of our family.She left him and ended the marry and is with someone else now. His uncle is the one marrying us. He and FS are also great friends so FS asked him to be his groomsman. Problem is my sister who I talk to every 6 months (if that) states she will not be apart of the wedding if we keep him as a Groomsman. Should I drop him or not?