Single to dual M/C. Some specific queries

The newer distribution block does more than "detect" a difference and turn on a light. In the event of failure, a metal "piston" moves in the failure direction and blocks any flow of fluid to the now damaged line, not allowing any wasting of the fluid. This movement of the "piston" also grounds the warning light switch cause it to complete the circuit and now go on. The OP can hook up his M/C any way he wants too.