we have had a few threads like yours in the past.
the peeps that had the special dietary needs contacted the park for advanced information.
they were issued the info that was requested.
contact guest services and let them know what you need for your family.
it might take a few days for the information to be gathered for them to send to you.
some of the restaurants in the park, city walk and the hotels can be contacted directly.
i'll try to pull up some of the past threads later this weekend.
i do remember some past trip reports had sections in them that contained the special dietary needs.