I know how to get a crash hard dummy but I keep seeing crash comps with more then one and I haven't figured it out other then going into the map editor and stuffing the dummies in there with their feet dangling through the floor lol.
Use this: https://www.beamng.com/threads/unsupported-temporary-patch-for-driver-passengers-and-loads.74427/
Crash compilation channels usually use private mods for dummies, that have features you can't get yourself... There used to be another mod for it but it's broken. Also the CrashHard dummy used to have an option for multiple dummies in Pessima but it was too laggy so it was removed.
I've heard if you chuck a vape into a Subaru and wait, they are drawn to it like cats to boxes, so after a couple hours you should have what you want. this is a joke...
large bump! (sorry) but it USED to! i am glad that crash hard dummy will get updated with more passengers, atleat thats what i saw in a video
if you want to fit the dummy inside the car maybe use Alt + F11 for world editor, or use the link @Turbo49 posted .