PlutoPony said:
Another solution would be for your parents to go thru security with your sister and meet you at the gate.
Deffenm,
I agree with PlutoPony.
I would recommend checking with United Airlines ahead of time to determine exactly what your parents must do to get permission to escort your mentally challenged sister to the departure gate.
Forty minutes should be enough time for you to exit from your inbound flight and to go to your departure gate if your inbound flight is on time. United has a huge operation at Chicago-O'Hare, spanning several concourses. You would be much better off being able to use your time to go to your departure gate, not having to find your sister at one of the security checkpoints, and then having to rush to the departure gate. Also, keep in mind that flights begin boarding 30 minutes before the scheduled departure, so 40 minutes isn't really 40 minutes.
Another thing to work out with the airline ahead of time is that you need to accompany your sister on the flight to Orlando. In other words, if your arrival at O'Hare is late and you're put on a later flight to Orlando, your sister needs to be put on the later flight with you not forced to fly by herself and to arrive in Orlando by herself.
I just looked at United's website, where I found the following at
http://www.united.com/page/article/0,6722,1082,00.html
Cognitive and developmental disabilities
United will provide assistance to individuals who may need guidance within the airport. However, an escort is not available to remain with the customer. Passengers who require personal or continuous attended care will need to provide their own attendant.
So that's another possibility. However, I would think that United would prefer family members to provide assistance, so I would think that United will be accommodating to your requests.
I was actually hoping to find a Special Needs phone number for you at the website, on the assumption that an average reservation agent may not be familiar with how to handle your somewhat unusual requests. As usual, if you get someone who only seems capable of saying no, ask for a supervisor. You may also want to ask if United has a corporate department that deals with Special Needs; I assume they do.
Good luck. I hope you have trouble-tree travel and a fun WDW vacation!