I'm close with my great aunt and planned to invite her to my wedding, but I barely know her adult children and had no intention of inviting them. Over the summer we had lunch with aunt and one of her daughters, let's call her A, who rudely insinuated that she expected to be invited along with her sister J. We said something about a small wedding and bean dipped. Later my aunt let us know (via word of mouth through my brother) that she really wanted A to come as her traveling companion. Fine. We had room for one extra person. A is single, so I gave my aunt a +1 on her STD so that she could bring A. That was our solution so that we wouldn't be "choosing" to invite one sibling and not the others. The STD said "Great Aunt Nelly and Guest", guest being singular.
The day before Christmas we visited with my aunt and some other close relatives, and when the wedding came up we made it clear that we are doing a small wedding with only our closest family and friends. I hoped this would get the message across that we didn't intend to invite second cousins. It didn't. Aunt cornered me on Christmas Eve after I'd had several glasses of wine and said, "So it's okay if J comes to the wedding right?" I'm thinking, sure, if cousin A can't come then it's cool if she brings cousin J. Nope, she proceeded to say that she was going to book a hotel room for her, A and J after the first of the year. I was completely caught off guard, and I'm pretty sure that was her intention. I'm mostly just annoyed. I don't actually like A but wouldn't mind her
coming if my aunt needs a companion. I like J alright, but if I send her
an invitation then I have to invite her husband, and then her brother
and his SO would probably expect to be invited also. We can make room
for the two daughters but just don't have room for anyone else.
TLDR: I was only going to invite my aunt to the wedding, and now she has extended the invitation to two of her daughters. So what would you do in this situation? I'm thinking I might only send an invitation to my aunt with a +1, and if she calls me and says that she already booked travel for both daughters, I'll tell her that's fine and we look forward to seeing them. Is there a better way to go about it?