I have an issue, and any advice on how to handle this manner would be appreciated.
The situation: I am getting married this July in Kentucky. Most of my family is from the Chicago area. Because my mother is very close with her cousins, our guest list is inflated with people I would not necessarily invite if it were only up to me. However, we made some compromises and agreed that her cousins would be invited, but not their children. Now one of them keeps talking about how the whole family will be there (including her two college-age kids who are not invited). I would happily apologize to her and explain the predicament, but the family is going on vacation in Tennessee right after the wedding. So if I say her kids aren't invited, I guess they would sit around in the hotel room that night with nothing to do, which I think is unreasonable. But if I let them come to the wedding, that could open up the floodgates for the rest of the cousins to bring their kids, and we simply cannot afford that. Additionally, I believe that would cause tension and drama in the family with some people being upset that another family's kids could come when theirs could not.
Help please! She has not formally RSVP'd yet, but I know that when she does she will include her kids, and I would like to be prepared before that happens.