Well you can always write a script yourself and send command to OpenSprinkler to open zones in any pattern you’d like. A single firmware is not going to fit everyone’s need. The reason we make the whole product open-source is to give users the freedom of modify the software in any way they want.
Also, the firmware supports up to 40 programs, so technically you can create many programs to define when does each group of zones start. So in theory you can use multiple programs to do anything you want. It is certainly tedious and difficult to update this group of programs, but it should be able to achieve what you need.
If you want to hardwire multiple zones to the same port, please note that a single port can support no more than 2 parallel solenoids. Each solenoid draws 250 to 300mA holding current, and 500 to 700mA impulse current. The triac on each zone cannot drive more than 800mA to 1Amp max, so it can’t do more than 2 zones. You can always use an external relay, which can drive amps or even tens of amps. That way one single zone switches the relay, and the relay in turn switches high current load.