So... much pain and suffering on this one but I have some definitive observations.

Connecting multiple processors on the network does not work well or at all unless they are part of a master/slave zigbee configuration. It does not matter if they are in separate programming files or if they are using zigbee or not.

I inherited a Yacht system to upgrade...

1. 2x RP6 with RM433 gateways connected.
2. 4x XP3 with RM433 gateways connected.
3. Older M2 Remotes

I replaced the RP6 units with XP6s and added two more XP3 processors. After speaking with RTI in advance, I decided to keep the RM433 units and stick with one way control because a) I did not want to rely on a single processor, b) I could not get Zigbee receivers for the XP6s units in time to execute and c) I was not sure I could get a reliable zigbee mesh network established on this large yacht for all areas without having to add wireless repeaters. I replaced the M2 remotes with 8 T2i. I used ID9.

My understanding from RTI was...

1. As long as the units were not using zigbee, no problem or...
2. As long as the non zigbee reliant processors were in a different file, no problem...

My experience...

1. I configured and tested the first XP6s using the RM433. All good.
2. I added to the same file, plugged in and configured the second XP6s. Behavior was strange. All IR ports would flash despite having them routed and nothing would respond to control. The first XP6s continued to function fine.
3. I moved onto an XP3. After I aaded to the same file, connected and configured it using 433, the processor would recognize the 433 triggers but nothing would happen. I switched to zigbee and the remote would make intermittent connection to the processor. Control would also be intemittent.
4. I decided then to make this first XP3 a master processor with five other slave processors in their own file. This worked for 5 of the six processors. The sixth would not connect to the mesh network because of distance and contruction materials I assumed.
5. I returned to the6s XP6s and nothing worked... as in NO 433 remote triggers were being received (no light flashing). I removed the first XP3 from the file, reloaded and still nothing worked.
6. I then disconnected both XP6s processors from the network and reloaded via USB. They worked.

Deductions... considering discussions with RTI, reading RTI documentation (not consistant with my discussions on the subject) and experimenting (not consistant with either)...

1. You cannot have multiple processors on the network without them ALL being part of a master slave scenario OR...
2. You cannot have a larger processor on the network that is NOT part of the master slave setup AND not designated as the master processor.
3. You likely can have multiple primary processors (zigbee or not) so long as they are not connected via ethernet.

This is dissapointing because it prevents me from my prior methodology of implementing larger systems quickly through a process of copy-paste with remotes that are room assignable while still having some sort of remote support availability. I do this to reduce service liability and provide a way for the clients to continue to use all rooms in the event of a remote failure.