Forgive me if my ramblings are stupid, but I don't know how much experience you have with RTI.

First thing: Make sure in the Properties of each remote, that they are routed to correct ZRP6. Properties/Output/Default System. The default seems to be that the remotes are set to the first RP unit in the system file.

Are there four Tivo's... one dedicated to each system?

Is there any need for a remote to talk to different RP units? Example: Room ONE remote needs to talk to Room THREE ZRP6? That could be a problem with zigbee... done it a bunch using 433, not sure how it can work with 2.5. I would think that you would need to hardwire the RP units together...