Here are some helpful information if the family member is on a special diet.
Table Service
For many people who are on the spectrum, they are on a special diet and it may be hard to get what they need. Disney is very accommodating for those with special diets but also those that have allergies to certain foods. Part of the planning process is determining what restaurants you may want to eat at. When making your dinning reservation for table service venues, you should let them know at the time of the booking that you will need special accommodations. 14 days before the reservation you will need to email them at SpecialDiets@DisneyWorld.com. When you check in, you should remind them of your requests, even though it should be in the reservation system. They are very helpful in finding alternatives for you to have a nice meal. The key is communication with them to let them know what your needs are so they can help you.
Walt Disney Worlds Website on Special Dietary Requests
Counter Service
Counter service restaurants can also help you with special meal requirements while you are at the park. When you get to the point where you order your meal tell the cast member taking your order that you will need to order a special meal because of dietary needs. They have special menus that will allow you to chose something that will suit your needs. The selections they have may be limited in selection, and it will also take longer to prepare compared to a normal meal so you may have to be a little patient with them. Counter service restaurants will try and help you as much as possible and again communication with them about your needs is key to a meal that will suit your dietary needs.