When FI and I had some unexpected changes in our budget, we cut down the guest list by agreeing that we would only invite family members we see at least once every couple years. It seemed like the most logical way to prioritize. By this criteria, we will invite my great aunt, because I've always been close with her and see her several times a year. We had not planned to invite her children or grandchildren (my second and third cousins), because I don't have a relationship with them and only see them every 3-4 years.
Then this weekend, my brother visited with our aunt and told me that she had mentioned that she wanted to bring one of her daughters, I guess to have a traveling companion. I understand that, and we could accommodate one additional person. The problem is, we invite one of her children and not the rest then there will be hurt feelings...but inviting all of her children and their spouses adds an additional 7 people, and then they would want to bring their kids. We just don't have space for that many more people.
So the solution we arrived at is to give my aunt a +1 and let her decide who to bring. Would this be okay? Or is it a bad idea? She's a Miss Manners enthusiast so I need you ladies to check me if this isn't etiquette-approved.