Z21 and Signalist SC1

[RomneySands]

I have four Absolute Aspects O gauge GPS units. Wonderful pieces of kit! They are connected to a Signalist SC1 decoder. My main controller is a ROCO Z21. Thanks to lots of help from Paul at Signalist they all work perfectly but ....
With help and by changing the value of CV37, when I power off and on, the SC1 resets all the GPS units to stop ie red and white light at the bottom, side by side.
However, if I leave one of the GPS units on go ie diagonal two white lights when I power on and off that GPS will come back on as stop ie red white light at the bottom but the display on my Z21 will show that signal as green on the display on the Z21 ie two white lights. It is easy to just cancel it by tapping the screen.
Paul at Signalist suggested putting a switch on the SC1 and I tried this. So, if I power of and switch the SC1 off before I power on and then switch the SC1 back on after the Z21 has powered up then any GPS units I have left on ie two white diagonal lights come back on in the state with a green light on the Z21 track and accessory screen.
While leaving GP signals in go mode ie two white diagonal lights is bad railway practice and I should cancel them after a loco has passed is there some way of changing a setting on my Z21 to recognise that a GPS has been changed by the programming of the SC1 and it, the Z21 should change the signal on its display from green to red without the need for me to install a simple on/off switch. Yes, I understand good railway practice should prevail but surely the technology should cope with what I am trying to do. I understand from Paul at Signalist that it is something to do with reset packages but exactly what they are I have no idea at all! 
Thanks in advance for simple explanations.

[RexAshton]

Try posting this in the DCC section. You should get a better response