Remote controller unit

I have one location that runs only two valves. It does have AC with an old basic controller there. I have two other Rachio units around my property, running almost 20 zones. I’d love for you to make a wireless “extender” unit that I could plug those two remote zones into and that communicates with one of the master units. It’s too inconvenient for me to run wires there, and I can’t justify spending hundreds of dollars for 2 more zones. It could even be battery operated with an optional transformer. Thank you.