I just started getting RSVPs for my wedding, and I was super excited...until I opened one from my married friends. Long story short, they're raising their niece, who is in elementary school, and they added her on the RSVP. I didn't address the invitation for the family, just my two married friends, and they clearly haven't gone on my wedding website to see that it says this will be an adult only wedding.
I obviously can't tell them the real reason why we're not allowing kids, which is because of my fiancé's niece and nephew, who are horribly behaved children. We've already postponed this wedding twice because of the pandemic, and we want a peaceful day without worrying if one of the kids will start screaming during the ceremony or knock stuff over at the reception. Our venue also doesn't specifically cater to kids, and we don't have it in our budget to provide "entertainment" for them.
Any advice on how to tell my friends they can't bring the little one? I don't want to cause any bad feelings or ruin a 10 year friendship.