Welcome to the Disney Parks Moms Panel Debbie ~
I completely understand making sure your children's needs are met and making sure that they are well fed during your trip.
My son is on a special diet and while his needs are not life threatening, it is difficult for us to find things he can eat in the parks so we always bring food for him into the parks. You will not need medical documentation in order to bring food in but there are a couple of things to keep in mind. Glass containers other than baby food jars are not allowed in the parks so make sure you store it in something else so that you'll be allowed to bring it in.
Table Service and Quick Service food locations are not allowed to warm up food brought that they do not prepare. I am sure that with your children having life threatening food allergies you can appreciate that to avoid any type of contamination. If you want to warm up anything in the parks, you can visit a
Baby Care Center - there is one in each of the theme parks.
Please feel free to visit us with all of your planning questions. It is our pleasure to assist you!
Wishing you minnie magical memories :-) Allison V.