It sounds like what you are asking is the ‘Master Station’ feature, which OpenSprinkler already supports. Go to Edit Options -> Configure Master, and you can set any station as a Master Station. Once set, that station on the homescreen will have a M symbol to indicate it’s master. All other stations by default are set to activate the master whenever they are on. You can individually set any station to not activate master if you want. Also, OpenSprinkler supports up to 2 different master stations (the Configure Master allows you to set a secondary master).