Ok - so here’s a video of the problem so far.
Essentially I have two versions of the same geometry - one unshattered, one shattered. The unshattered version is unhidden at first, the shattered is hidden.
At frame 30 they swap visibility with simple keyframes in the attribute editor. The shattered version is parent constrained to the unshattered version in order to inherit it’s current position at frame 30.
While this may not be so necessary for pre-animated unshattered geometry, it will definitely be needed for dynamic unshattered geometry as each simulation has a slight degree of randomization.
The problem:
The parent constraint also transforms the simulation’s world coordinates - as well as, it seems, the rest of the rigidbody locations. It’s almost as if it’s linking the entire simulation to the unshattered object.
What I think needs to be done is to unlink the constraint to the dynamics simulation and world coordinates. How to do this…? Looks like I’ll have to RTFM =\
EDIT: OR find some way of keyframing or triggering dynamics to be applied to the object in realtime at a specific frame. Not sure if this is possible, however, as rigidbodies seem to need to be defined with weights at fram 1 for them to interact. Hmmmm