Yes, it's a wedding one 
DP and I are getting married later this year, We've thought a lot about it but decided, for a variety of reasons, that we will have a child-free wedding.
Some context: We are both older (late 40s), second marriage, no young kids and the majority of our friends and family (with some honourable exceptions) are the same. The venue we've chosen is meaningful to dp and me but not terribly child-friendly and we are limited on size and budget.
Pretty much everyone has been fine about it - except a friend of dp's who has kicked off because his small children - who dp has met once and I've never met - are not invited. He's been texting dp frequently asking if we can change the 'rules' for his family because they can't find suitable childcare and therefore they want to bring their two kids both under 6.
Now, I understand that childcare is a PITA, expensive and annoying. But if we change the decision for them we have to do the same for everyone else and that will have major implications for our budget and for our guest list (ie we will basically have to un-invite some friends and family in order to accommodate small children we don't actually really know).
AIBU to think they are being CFers and should either refuse the invite or sort out some childcare and either way not ask us to change the decision we've made?