My goal is to have a barrel that is falling emit particles from the top while rolling around.

So have a RDB sim of the fall and read that into a file sourced to particles, but I lose the group that was on the geo I wanted to emit from.

I'm sure I'm missing something basic in my understanding.

I think I need to use a sop solver plugged into the rigidbodysolver post solve to transfer the attributes from sop->dop.

I've tried that but still not seeing the groups transferred across.