New Layout

hello ,

I suppose you are running DC
you to put your isolation joiners in place of each joiner between the switches, on both rails, that means 4 insulated joiners.
then you have to put the small screws under your swtiches to assure that the small section between the insulated joiners and the frog is powered.

and of course you need two power supply for your future plan.

But I would build as the future plan immediatly, and connect your alone power supply on the two loops.
In the future you will only need to connect your iner loop to the new power supply, and let the other for the outer loop