Alternate physics engines as plugins with interoperation between them

It would be nice to see the ability to implement alternate physics engines as plugins with inter-operation between multiple engines. This would come in useful if someone wants to use a combination of say, PhysX and JSBSim, PhysX and Bullet, or Bullet and JSBSim. The reason this would be useful is some engines are better suited to some things, where others are better suited toward other things. The ability to register components as abstract physics component types, and the ability to switch between engines grammatically, for that component (not for all components of that type, but just that component) would allow things such as having an aircraft that flies using JSBSim for flight dynamics, but upon impact with the ground works with PhysX.

Bump! Trying to do this as well, but not really familiar enough with how the UE4 engine couples to the PhysX libraries. Did you ever find out where to look?