I would like to have a number of active RB objects set to animation so that they do not fall until their respective animation check-boxes are key-framed off. For a few objects, this can be done manually, one-by-one. My objective is to have perhaps hundreds of such objects with their respective key-frames corresponding to certain actions in the scene. For example, as an animated object gets close to one of the RBs, the RB's animation check-box gets keyed off and the object falls.

Can a driver be used but reacting based on distance from the RB instead of some rectangular coordinate.

Any ideas would be appreciated.