It looks like both requests are about having more than 1 master valve. The firmware currently only supports one master station. However, you can make use of the ‘parallel station’ feature. Specifically, you can define a station as a ‘parallel’ (i.e. non-sequential) station. When creating a program, include that station as well, and set its time to span the whole program. This way, that station will turn on when the program is on.
This is assuming you are running the Unified OpenSprinkler Firmware, which supports parallel stations.