Ignore child intercollision, not parent-parent

I have a ragdoll object made of up several objects (and box colliders). I do not wish it limbs/torso to collide with one another, yet be able to collider with other ragdolls.

How can I go about doing that?

 EmptyObject
 -torso
   -head
   -armupperleft
    -armlowerleft
   -armupperright
    -armloweright
   -legupperright
    -leglowerright
   -legupperleft
    -leglowerleft