I invited a friend and her family (husband and two children) to vacation with us at my parents' home this summer. My parents were willing to host all of us, four adults and four children in their home.
While at a party at my friend's home, she began discussing the trip in front of her party guests. One guest, a friend of hers, commented that our summer plans sounded like fun. In response, my friend invited her friend and two children. My friend turned to me in front of everyone and asked if was OK that they join us.
I felt as if I were backed into a corner and had to be amenable to the invitation or risk upsetting and/or angering anyone. I told my parents and they were quite upset that my friend invited others to their home without any consideration.
Including my parents, there will be 13 people staying at my parents' home for five nights. My parents are older, and I cannot expect them to feed all of these guests. I want to put stipulations upon the visit – for instance, guests provide their own food, beverages, linens, etc. I am not sure how to handle this situation without upsetting or angering anyone.
The rudest thing here – and therefore the most worthy of any anger or upset A. was a guest's presuming to invite people to join her at the Giant Doormat of your parents' home when your parents weren't even there to say no. That's actually about three rudenesses in one, a Mallomar of rude.
Because of this plain violation of good manners, you could easily have said no without risk of upsetting anyone (meaning, anyone who has manners, the only people you really need to worry about). "Gah, no, my parents can barely host eight of us as it is."
You could also so easily have punted: "I can't speak for my parents – let me ask." Then you'd be out of the "in front of everybody" corner and able to spike the idea privately the next day.
Still. No form of "no" would have been rude because the only rude answer was "yes": It was rude of you to impose these extra guests on your parents just because you didn't want to look like the bad guy.
Fortunately, even though being solicitous of people to the point of possible self-injury is apparently a trait that runs in your family, your parents – and you on their behalf – are fully entitled to rescind the (non)invitation: "As I talked to my parents, I realized I'm asking way too much of them to host so many people. My mistake. They feel terrible, but I assured them you'd understand." Then you can offer to help these add-on guests find a hotel.
Just don't let them phantom-obligate you into picking up the tab.
Kidding aside – have you ever considered working with a therapist on assertiveness and boundaries? When you don't feel empowered to say no, even to someone who is asking for something that's clearly over the line, an awkward social situation is going to be the least of the trouble that finds you. Please at least look around for other signs this trait is wearing you down – or trickling down to a new generation.