So, I'm starting this off saying the issue itself has been resolved I'm just annoyed a little because they know we're on a tight budget.
So the best man is married, his wife is coming. They decided to invite her sister (fiance knows her, I've only met her like two or three times).
Best man has been helpful so if they asked we probably would've said okay. His wife knew he'd be busy and wanted to feel more comfortable. I think she asked him, he said he's sure it's fine, then forgot to ask or tell us. (Although she knows some other guests).
Our invite even said as nicely as possible no plus ones. We invited everyones significant other, and everyone knows at least a handful of people anyway.
We told him it was ok but not to invite people. We're finalizing things with the caterer this week and we easily could've not even known until the day, we just reached out to see if they wanted to room with someone to save some money and he said he didn't think her sister would want to share a bed.
Is this a common phenomenon?