How to add collisions to car seat? (trying to place the stig ragdoll as driver/passengers)

How to add collisions to car seat? (trying to place the stig ragdoll as driver/passengers)
Hey there. Basically my problem is that I'm trying to manually add the "stig" as the driver on modded cars. I can't add it via the "passengers and load mods" as I don't see the option in the car modification menu.

But the problem is even when I try to manually place it on the seat, there is no collision on the seat and the stig just goes right through, and falls on the actual frame of the car instead.

Video:


So does anyone know how I can collision to the car so that it collides with the stig/ragdoll?

Thanks

 

you have to mod the seat jbeam