I'm normally a pretty level-headed person but now that RSVPs are coming back, I'm really starting to stress out. No one seems to know how to read an invitation and keep adding more and more people onto their response cards. Thus far it has been mainly friends - one girl decided to try and invite her parents and sister - but now it has reared its head on my side of the family. Sigh. I don't think it is really all that unique of a situation and yes I'm looking for validation but please tell me if I'm completely out of line and need to calm the fuck down.
Basically, through my dad's insistence we invited his Aunts and Uncle as well as one cousin (and her husband) and their oldest daughter who is 18 and I actually know somewhat. Cousin has 4 other children that are all under 18. I sent out two invitations, one for the daughter and one for the Cousin and Husband. My parents just saw these people yesterday and they informed them that they are all, all 7 of them, coming. There was some prior miscommunication between my parents and I that has exasperated this problem, because for some reason they didn't mention the younger kids but assumed I was inviting them and I thought since they didn't mention the younger kids that we weren't inviting (and if I had known their intention WAS to invite the younger kids, we could have cleared this up then).
So now we are at an impasse. I have told both of my parents that those kids will not have a seat at my wedding if they don't take care of it. I don't want these kids, who were not invited, at my wedding. The invitation specifically only said Mr. and Mrs. Smith. My mom said that if she ever received and invitation like that that she would just assume her children were invited because to not do so would have been incredibly rude. My dad says I should have been more clear that the children weren't invited. They both say they refuse to deal with the problem and unless we don't get a lot of people declining than they won't talk to them and inform them that their little preciouses aren't invited. They also said not inviting the children is akin to not inviting someone's husband or wife.
Any advice? Am I really the brat that my parents are making me feel like? Did I commit a major etiquette faux-pas by not inviting these children? I keep thinking if this is the hill I want to die on, but I don't want these kids and for some reason this guest-issue is pushing my buttons a lot.
ETA: My parents paid for the venue deposit, photographer, my dress and the pop. FI and I are covering everything else.