In my case I have 2 irrigation control boxes, one for the front yard and one for the backyard.
Both control boxes have 4 zone valves and 2 masters valves for municipal and borehole water.
It would be great for me to have 4 master valves, 2 would be used for the front yard and 2 for the backyard.
That way I could get rid of the manual selector switches I currently use to select between water sources for the front and backyard.
Typically I’d run for the front yard zone1 (master1) municipal water, zone2 (master2) borehole water, zones3-6 irrigation.
Similarly for the back yard zone7 (master3) municipal water, zone8 (master4) borehole water, zones9-12 irrigation.