>>2952568
So they are using a UHF link to separate the two CBs because the output will come back into the input channel even if they are separated on the CB band, that's normal, all VHF, UHF relays use huge cavity filters to avoid that. 10m relays have the emmiter and the receiver on different sites.
These cavity filters are very steep and very narrow so that for example for a R0 VHF relay the emitter at 145.600 MHz doesn't trigger the 145.000 MHz receiver.
Another way to do that is have a CTCSS squelch for the receiver and the emitter doesn't has CTCSS.

Cavity filters dimensions are of course proportional to the wavelength so they are ok for UHF, big for VHF and for 11m they would be about 2.5m long
http://www.amalgamate2000.com/radio-hobbies/radio/cavity_resonator_for_29__mhz.htm

Not impossible to make apparently