Do the systems have overlapping coverage? If they do, then this will not work at all. The subscribers will not know which system they are talking on. Since audio will only be routed to the system who gives the radio the "go ahead" message. So user 1 will not know if their audio is being passed on system a or system b. This makes predicting which group of users who will be receiving your message very difficult. If the systems are not within range of each other, then it will work only when the cap plus system rest channel is sitting on that one frequency. Cap plus by default changes the rest channel every few minutes or few transmissions. You can alter this behavior, but not reliably to make what you want to happen work properly. The only conditions I see this working under areif all of the following are met:
A system are not within range of each other. Subscribers will never be able to hear both systems at the same
B all frequencies, slot numbers, and color codes are the same
C all talkgroup numbers have the same function at each site
What are You trying to Do? TT.