Possible trip with DSister

[Scotfan]

We live in Scotland and are semi-regular visitors to WDW (4 times since 96), who now own at Vistana.
My sister is 31 and is severely mentally handicapped but is NOT physically handicapped in any way, we think that she would love the sights and sounds especially with the characters, so are starting to think about a trip to include her with myself, DH, 2 DS(5&7) DM&DD (Both mid 60's).
She cannot communicate in ANY way other than laugh, usually at my expense, or scream loudly when she is annoyed/upset.
Would we be able to get a GAC and could the whole party stay together? She wouldn't tolerate queues and at any shows we would have to be at an exit in case she decided she didnt like it.
Would there be an area where we could just appear to see the fireworks or Fantasmic etc as she loves Fireworks but no way would she tolerate standing around for a while before they started.

I realise that there are a lot of questions but I dont want to take this trip any further if it is going to cause more problems than it is worth for her sake.
Thanks in anticipation!

 

[SueM in MN]

Welcome, Scotty.
Feel free to ask as many questions as you can think of. We have lots of people here who are willing to share their experiences. I'll start out and I'm sure other people will add info.
GAC: In case you don't know anything other than the name, GAC stands for Guest Assistance Card. It's a way for the CMs at attractions to be able to see you need some extra assistannce. That might be a quieter place to wait, being able to wait out of the sun or to be able to use an entrance without stairs. Many people with physical disabilities don't need a GAC; a person with a wheelchair or ecv will be using the handicapped entrances without having a GAC.
In my opinion, you won't have a problem getting a GAC for her. To get one, you will go (with her) to Guest Services in any of the parks. Be ready to say just what you wrote in your post, that explained your needs quite well. The GAC is usually valid for your entire trip and is for the person with a disability plus up to 5 members of their party. But don't worry about the number, we have been able to get a GAC for DD plus 6 people when we had 7 in our party.
All of the shows have well marked exits, so you can just seat yourself there.
Fireworks: For Illuminations at Epcot, we don't like to use the handicapped seating. Our DD does not like to stay in one place and she likes a little "personal space." We've found the handicapped areas are usually quite crowded and "busy". Depending on the time of year, you need to arrive quite early to claim your spot. Wheelchairs and ecvs are lined up along the fence and other people stand behind. My DD has never been patient enough to make waiting there pleasant and severl times we had a very obstructed view because she was behind a tree.
You can find good viewing spots all along the fence at WS and often even find a bench. One of the nice places we have waited for Illuminations is a small seating area by the Outpost (refreshment area between China and Germany). The view was quite good, although it looks like it will be obstructed. It's also a little more private and by moving the chairs and tables a bit, you can get a spot where there will be rocks on one side, so no one would be able to get right next to you. My DD liked it because she had a table for eating and drawing. We actually were waiting there for over an hour one night, but DD was fine with that since there was a table.
If you want to be more away from the crowd, you can find a spot in front of the Odyssey Center (near First Aid) where you have an overview of the whole lagoon. You will see the fireworks and hear the music, but the volume is much less and there will be almost no one there.
Fantasmic: You would be able to use a GAC to sit in the handicapped area, which is the top 2 rows of the auditorium. There was a thread about using a GAC for Fantasmic.
Parades: For MK parades, an out of the way place to still see from a short distance is the bridge to Adventureland (by Crystal Palace). If you look toward the castle, the parade will go over the bridge that goes between the circle and Frontierland. If you are in Fantasyland when the fireworks go off, you can see them over your head. Really neat.