record world position of parented object to keyframe

Hey All

I’ve got an object parented to a whole bunch of other objects (car trunk parented, to car body parented to RIG, parented to empty constrained to copy world location of another empty so I can offset, following a path)
Basically I want to have some other objects rattling around in the trunk, preferably using physics. However, since the actual world location of my trunk doesnt move (see about parenting structure) I can’t get the objects to react in the trunk correctly.
Is there a way to record the world location of an object in a parenting structure to LocRot Keyframes? Or, am I crazy and is there a better way of doing this entirely?

Thanks all.