An EVC user and a child with ADHD

I have avoided asking this question because I don't want to upset anyone or anyone to think i'm looking to abuse the system, I'm not.

Here's my problem. I will be needing an EVC. I can walk and stand, even dance, but because of my arthritic knees and back, I can only do it for 5 minutes or so before I have to sit down. There is no way I could do Disney for 7 days without one.
I will also be with my son who has ADHD.He is 5 years old He is the sweetest thing in the world, has so much joy in him and is all boy, but no way would he stay in line.
My gf and friend will be there as well. When it comes to standing in line, I don't mind staying and either my gf or friend would stay with me, but is there anyway, they will let us stand in line and let my son and the other person wait outside and entertain us and then let them in line?
I don't want people to get angry, not because of me as much, but my gf is very protective of our son.
another issue is we are going over thanksgiving.
I'm looking for the best way of handling this with out cheating the system or upsetting other guests who are in line with me. I know for me, I dont' have any problem with someone holding a place in line, none at all, but I know some do.
any suggestions?

thanks.

I think getting a DAS card for your son would be the best option. You and your gf would then be able to go with him. I would also make sure I had FastPass+ ready in advance for the rides you really, really want to not miss.

I agree. The DAS would probably be okay for your son. That's not cheating the system. It's what it's designed for. Go to Guest Services and ask for the DAS for your son. They'll get his information and give you a card with his photo on it. You present that card to the CM at the ride and they'll give you a return time that is based on the standby line time at that moment. So, if the standby time is 50 minutes they'll give you a return time for 50 minutes. Then you come back and enter the FP line. During that 50 min timeframe you can do whatever you want - relax, eat, shop - so your son doesn't have to wait in the long line.