This is an aweful spot to be in. I know exactly how you feel as we went through something similiar but it was with FIs parents. When we first got engaged we sat down and made a list of who we were going to invite to our wedding. We want just a small wedding as we are paying for it ourseleves. We had decided who we were going to invite and it included grandparents but not aunts uncles or cousins. We send out our STDs to only the people on our list. Everything was fine until about two months later when my FIs mother told me she had invited some people to come to Jamaica to our wedding. I was absolutely furious, as its our wedding not her wedding, and the people she invited were friends of hers that I have never ever met in my life. I'm kind of a private person and didnt want all these extra people that I dont know at my wedding. I clearly explained to her that she needs to tell them they are not invited and she told me I would have to tell them. Needless to say I dont have that type of personality to call someone I dont know and tell them they cant come to my wedding. To get around it we sent invites to only the people on our list and excluded FIs parents friends that they had invited. Just a little while ago FI mother was mad that we never sent invites to her friends. She told us that they will be coming to Jamaica whether we like it or not. I told her that was fine, they are more then welcome to come to Jamaica the same time we will be there, but they will have nothing to do with my wedding and will not be included in any wedding events. We are about three months away from my wedding and so far none of these friends she invited have even booked to come (they were not allowed to book as part of our group, they had to book on their own) so whether or not they will show up who knows. It is a tough spot to be in. I guess you just really need to sit down with your FI and decided if its important or not to have those people. If not, dont send them an invitation. And be prepared to have some people angry for not receiving an invitation. Also, some people may show up at your destination anyways, and there is really no way to stop that.