OK, so here is the part I'm a little less sure about and may require the relays as an extra layer of isolation- both for current reasons as I do not know the current of the reatrax switch motor coils- and part 2- the anti derailing function most likely also is seen on the control wires to common. This poses NO PROBLEM if we use additional relay isolation- the relay contacts simply short one control direction lead of the switch to common- and so it won't matter. The controller- something like a QSnap or equivalent- can drive the relay coils just like a twin coil motor.
I don't know if this is additional wiring is absolutely needed- but I can say in O scale with derailments and other things- I think a good idea to protect your electronics.
