Hi CV8R,
The good news is I'm pretty sure it can be done. One general basic way I can think of is to just modify this script so that:
1. It adds an additional parameter like 'ID' where when called from EGIGeo each person passes their unique ID (1, 2, 3, etc).
2. Then something like a server variable for each ID is created with a value like 0 = away, 1 = home (may have to use a file or perhaps cookie instead?)
3. Prior to using curl to call zoneminder it would then check these variables. If any variable is equal to 1 (for home) it would then change the zoneminder state to home. Otherwise the state would be changed to 'away'. The effect would be if anyone is home then zoneminder is set to HOME otherwise it is set to away (as no one is home)
I'm not much of a coder either but I might be able to rig something up if you still need it?