@FlickingVees You missed a camp.
the camp that thinks that our job is to raise adults, ones that appreciate what effort it takes to save up and achieve things and not expect to be able to tag along to things just because they want to, or because they are resentful of the fact their parents have lives outside of being Muuuuum.
Our children will grow into young adults and grown adults and actually gain an enormous amount from making their own way, saving up and travelling without their parents, with friends of their own age etc
I asked my own DS if he wanted to go on a school trip abroad and he said no, he'd rather go on his own when he is older or with us as a family than go with the school and have an agenda/timetable to follow. Ok so he is still at school and these things change, but he gets it... I get it. I think he'd enjoy a school trip tbh, but I'll see if I can convince him before he leaves school, for the experience alone of being with his mates somewhere else.
You are very judgemental quick to call the OP and her friends 'old soaks' . actually the OP said they are more interested in fine dining, shopping and chatting than going out on the lash. its not about drinking, its about spending adult time with people you have a good deal in common with, on the same level.
By one of the party inviting ANYONE, it changes the dynamic, but inviting an 18yo it blows the dynamic to smithereens, she wants to 'Do Paris', see the sights etc, the other women on the trip are not there for this.
The only response to her nagging 18yo should have been 'This is a trip with my friends, I can't just take you without talking to them, at the very least I need to check to see they are ok with it, but bear in mind they may very well not be.'