Quote - anyone know if ya need groups for sure with bullet ?

For the record: Chapter 23 in Poser is the Bullet Physics chapter. As far as I know you don't need groups. Bullet physics defines these as objects. And they are labeled as 3 "types". Like Choreographed, Rigid and Soft Body. Choreographed objects are those which either remain stationary or are animated manually with keyframes. When assigning choreographed objects, you only need to assign the objects that you expect the other physics objects to collide with.

Rigid dynamic objects are those which will interact with other objects, but which will maintain their shape when they collide with other objects in the scene.

A soft dynamic object will change its shape or appearance when other objects collide against it.