Hi Alex!
Welcome to the Disney Parks Moms Panel! We're so glad that you found us hEAR!
I have a really tall-for-his-age
Mouseketeer too, and of the many times we visited Mickey's House before my guy's third birthday my verbal word was verification enough. At the worst you may be asked if she has her own ticket at the entrance to all Walt Disney World Resort Theme Parks, or how old she is at all
Disney Dining Locations where everyone older than 3 is charged, like at a
buffet or character meal; in these cases you'll simply state her age and you'll be fine to carry on with your Disney Day. While you shouldn't need to produce any physical proof, just to be safe, and instead of bringing her actual passport with you every day, you could always take a picture of her paperwork and store that on your phone.
Bonus Tips: Definitely keep tabs on all that is new and coming soon before your arrival by 'liking' and 'following' the
Disney Parks Blog across all their social media channels. Check out our Moms Panel
Video Library about how to Disney with little ones, and also our
Top Tips for exploring the 'World! (Well, the Walt Disney World!)
Thank you again for stopping by, Alex, and if you have any more questions we're all Ears!
~Kristen