I assume you are running conventional.
Isolate the center rail of the connector tracks that go through the wall from the center rail of the loops. Use three single pole double throw switches. One for each loop and one for the connector tracks that go through the wall. Connect the center posts of the SPDT switches one for each loop and one for the connector tracks. Connect the end terminals of the SPTD switches to the desired throttle control.
As for the turnout switches, since they will all be switched either to the main or the diverging direction, you can wire them all to the same control switch.