4 year olds on booster seats in car - how do you stop them falling sideways when asleep?

[sandyballs]

I really wish I'd brought seats with a back and a heat rest instead of the booster seats because when my girls fall asleep the end up almost lying across the back seat which is obviously dangerous if I were to have an accident.

I vaguely remember seeing something that goes over the back of the car's headrest to support them a bit more but can't think where it was.

Any ideas anyone because we're off on a long journey on Friday night and they are bound to fall asleep.

I only have 2 kids anyway and my friends kids are all over 11yrs. So not so much of a problem for me. I have never heard of cars with 5 seats not being insured to cover 5 people. Mine has 3 lap and diagonal belts in the back and is a big car but I don't think you could fit 3 stage 2 seats accross it. Don't fancy driving 3 under 4's about anyway .

BTW I am not using the cushion as a restraint, she is big enough that the belt sits in a good position in our car anyay, its just for comfort. She uses a booster in MIL's car as the belt sits higher on her. I was trained to fit and advise on car seats when I worked in a shop that supplied them.