DS2 is 4yo and has received an invite to a birthday party. It's at a public location (local church hall), in the late afternoon (4-6pm).
I'm really struggling with this one. I'd love to let him go, but keep coming back to these things:
- he's impulsive ADHD/ASD and constantly runs off, which means I would have to literally be next to him the whole time due to the location and how open it is (with a few different exits)
- lots of kids and noise (obviously with a party LOL) and he doesn't always cope well with the noise (sensory processing problems)
- often doesn't understand instructions for games and such due to language and communication delays/problems
- picky eater so won't eat a lot of food (including any cake that has icing on it)
- goes to bed at 6:30 every night, so this will seriously mess up his evening schedule and most likely affect his sleep that night
Yep. Okay. Writing it all out like that, I'm really pressed to find a good reason to take him other than "first chance ever to socialise with classmates outside of school." 
Perhaps better to have initial socialising with classmates on a smaller 1:1 scale with less chance of it all going pear-shaped?
sigh... I guess need to RSVP politely and decline carefully. Other parents have not been advised of the specifics of DS2's difficulties, although I would imagine they suspect something as he is the only child that gets walked out to his parents directly at school pick up.
Someone commented once on the "lovely door-to-door service we get." 
What do you do about birthday parties for classmates? This is the first one we've had to navigate.