Oi vey

I have a cousin who lives in GA with her husband, 2 boys (1 has down syndrome) and a little girl. I honestly didn't think they'd come to our wedding, what with it being on a Sunday, the kids having school, and well...kids just not being invited making it perpetually impossible....
Well of course she writes me excitedly 20 minutes ago saying "Yay! We are coming! I made sure to work our schedules around, and since the kids have never missed a school day it's no big deal."

that's what I get I guess for thinking I wouldn't have any issues with not inviting kids.
I then had to tell her (nicely) that kids weren't actually invited, which was easily the most awkward thing I think I've ever done....
BUT, she was super understanding and said she understands considering she and the hubby could use a night to just cut loose.
So, now I have to try and find a babysitter, but most importantly one who could watch the kids right near our wedding. Do you ladies know how I can go about finding a babysitter that would maybe just watch the kids for 5-6 hours at our hotel (where the rooms are blocked)? Is that normal or pretty weird? Also, do any of you personally know a good sitter?