To the dreaded inlaws. We fell out seven years ago and not really seen them or heard from them since. Dh sort of stayed in touch with mil but she has issues and gets very nasty. FIL has had a heart attack and we decided we needed to go and support rest of family (he won't see us). It's nearly 6 hours in the car, with my two Asd girls for three nights, with people who don't know the girls or anything of their dx! We have hired a lodge but I feel sick thinking of it. I'm taking the iPad and hoping I can join you lot and hide in here. Please keep me sane!
Lodge is good. Car journey.... Well, travelling is a life skill so that's 12 hours of practice in which you could reinforce car behaviour
'gentle hands', 'use the loo before getting in the car', 'gentle hands again', 'look for a service station, that's where the loos are', 'gentle hands for your sister please...', 'you've just been, I'm sure it'll be fine till the next services'
Or of course, put them in PJs, dollop of melatonin, and set off at 10pm.