First, you want to check out post 6 of the disABILITIES FAQs thread. That thread is located near the top of this board or you can follow the link in my signature.
It may be very helpful for you to think of using a double stroller even if all your children can walk the distance. A stroller can give separation from other guests and a safe haven/area of decreased stimulation for kids with developmental and emotional issues.
I would also suggest looking into a touring plan - popular ones are touringplans.com and easywdw.com
You don't have to follow the plan exactly, but just knowing which park and which part of that park is likely to be least busy will be very helpful to you.
Also, keep in mind that for many kids with emotional/developmental issues, a touring plan is helpful because it gives them predictability and a schedule for what is happening next. Many people find using a touring plan to actually be more helpful than a Guest Assistance Card because it is more predictable and can help you in places that a GAC can't - such as avoiding crowds just walking around, using the bathroom and eating.
The are some other things that may be helpful to you in the disABILITIES FAQs thread. Post 3 has a lot of specific information. I'd suggest looking at the YouTube link to an internactive WDW tour video that is in that post. It can be very helpful to actually see and hear what they may experience ahead of time. There is also a good book called WDW For Kids, by Kids that might be helpful. It is a WDW touring book fRom the viewpoint of children. Even if all your children can't read it, it does have helpful insights into which things kids consider to be scary or dark, etc.
Post 3 of the disABILITIES FAQs thread also has one area with links about communication devices and PECs, if your children use those. Even if they don't, you might be able to do some social stories that would be helpful to prepare your children.
Some others things to consider:
- if you have not gone anywhere similar, you may want to plan a day trip to somewhere nearby like a zoo or smaller amusement park. That will help you to plan out what may or may not work for you.
- bathrooms in the park. I don't know if you are traveling with just you and the 3 children, but if you are, you should consider using the Companion Restrooms if you will not be able to leave the children alone. Those are one stall bathrooms with a lockable door so no one can come in while you are using it. There is no privacy from the other people in the room with you (it's just one big room), but if you can't leave them alone and have no one else to leave them with, it may be your only option. The larger ladies roms also have large handicapped stalls where you could fit with all 3 children.
- restaurants. Your older children may be able to help you carry food to a table in the counters service restaurants, but don't be shy about asking for help if you need it.
- getting to the parks. Not sure whe you are staying or how you plan to get to the parks, but you probably want to prepare your children for the types of transportation they will be going on. If you drive, there are parking lot trams. The MK area resorts have monorails and/or boats and the other resorts have buses. Some kids with developmental disabilities really like the transportation as much ( some more) than the actual attractions in the park, so be prepared that you may have requests to ride the boats or monorails over and over.
- quiet places inside the parks. The parks have A LOT of stimulation, both visual and sound. Every area has its own themed music and/or sound effects. For some kids, this can be sensory overload. That is where a stroller can come in handy - even with a light cloth to pull over the front to really cut down on stimulation. Many kids also like earphones that cut down the sound - there are specific ones made for kids in bright colors that you can find on
Amazon.com. Some people get stickers and let their kids decorate them they ways they want.
Strollers can. Rented in the parks or you will find links to some places that rent strollers in post 2 of the disABILITIES FAQs thread.
- downtime for you. You didn't say if you will be going alone with the 3 children, but I would strongly recommend another adult, if possible. It is more stressful and more tiring taking care of children with special needs in an unfamiliar, stimulating environment. Having another adult to share the care with will help you to have th energy to care for the children and help everyone have a good time.
Also, if one child is having a bad day, that other adult could give that child or the other 2 some special attention. It would also be helpful where one or more children don't want to or can't go on an attraction that one of the others does want to do.