Does Disney require any form of age verification for children at check-in if you are on a vacation package with the park tickets and disney dining plan included?
If your child looks like he/she is 3 years or younger, then you will have no problems as just the "quick glance" method is used. Unless your child is unusually big for their age, you won't have anything to wory about.
because my dtr. was unusually tall and a week shy of 3 on our last trip. Many on Dis advised me (for my own peace of mind) to bring a copy of her birth certificate. I carried it with me everyday....but was never asked or even looked at funny when we rolled her thru in her stroller.
My kids are all extremely tall for their ages, and I've never been asked for any kind of ID. (I do make 6'4" DS15 and 5'11" DD13 carry their passports when they fly, though! They don't look like adults, but I figure it's better safe than sorry.)
When they were younger I just figured I had their birthdates on their insurance cards in case any one challenged us. Nobody ever did.