Is There an Inertia Like Reaction Force Acting Back on Particle A?

Space and time can be emergent from the quantum formalism. We don't know that it's true in any obvious way, but it's certainly conceivable. Decoherence is a dynamical phenomenon that spreads outward alight cone within parent space time. branches of the wave function are like or higher level emersion phenomenon. They are not something that exists at the fundamental level. It's human beings who care about the class a limit. It's not the universe that cares about the classical limit.