The first thing to note is that the main difference between OSBee and the main OS 3.0 is that OBee is designed for latching solenoid valves while OS 3.0 cannot operate latching solenoid valves. So first make sure latching solenoid valves are what you have, before going all way in to OSBee.
I agree with Mike that you may consider using a master OS system and the HTTP station feature to send commands to OSBees and that way you can have one central controller while the OSBees all become remote valve controllers. The master OS system doesn’t have to be a real OS/OSPi — it can be just a Linux system like a raspberry pi, because it doesn’t need to operate any physical stations, it merely serves as a central scheduler that sends commands to other controllers. And OpenSprinkler firmware can compile and run in any Linux system.