Previously she had, I assumed, jokingly mentioned bringing this friend to our wedding. Admittedly, I should have told her no at that time but I didn't really think she was serious. When we saw this post we were really confused - why would this friend of theirs who we have met one time think she was invited to our wedding? My FH messaged the girlfriend on FB and said basically he's sorry for the miscommunication but her friend is not invited. She deleted the post and didn't respond to his message.
Now the groomsmen is basically saying we have to let this friend come or he won't be attending the bachelor party. We decided to avoid drama to just let this friend, who again we have both met ONCE, come to the wedding but I am just blown away at the incredulousness of the whole thing.
Editing to add: there is a group of about 8-10 people/high school friends of my FH that she knows really well, that she could spend the day with while her boyfriend is doing groomsmen-y stuff/getting ready