ns79 - welcome to the forum.
What you are looking for is called "call forking". Any InboundCallRoute can be set to fork calls to up to 4 devices. In your OBi110 delete "ph" in the following InboundCallRoutes and replace as follows (I'm assuming that you set up Google Voice on sp1):
Voice Services > SP1 Service > X_InboundCallRoute:
{ph,pp(ob200123456)}
Physical Interfaces > LINE Port > InboundCallRoute:
{ph,pp(ob200123456)}
Where 200123456 is the number of the OBi100.
This arrangement will ring the phones attached to both OBi devices. Whichever OBi answers first will win the race and be connected to the incoming call.
I'm not a GV user, but I believe that you can only register one GV acount on one device at a time. If you had two GV accounts, one on each OBi, maybe you could forward outgoing calls from one account to the other. Maybe one of our GV experts would comment on that.