Clotted, I think you're right in saying the Qld Country Routes were not controlled from HO Res. My memory is fading but I seem to recall that they were treated the same as non-TAA 3rd level flights. If we recived a phone booking for any airline/route that was not controlled by us, we would either ring (sometimes telex) the nearest main TAA Office (Brisbane for the services you mention), they would then make the booking in their system (or make it with the respective airline or TAA Port responsible and let us know.
My memory recalls NN (need) requesting seats, the reply of KK (confirmed by respective Res office). Once we got a KK response we would then change our records to HK (holding confirmed). Waitlist I think was either WL or LL) and responses would be KL/HL. To confuse matters more, there were priority systems plus Freesale (FS) bookings that had to be confirmed even if no seats available. These FS were usually from International carriers as part of an International journey.
I can also remember that if we had to book someone on an Ansett controlled flight, we'd just ring them up (only a few doors away in Franklin St) and always found them to be just as friendly and helpful as we were. There did not appear to be any friction between the two sets of staff and in fact we often socialised with them out of hours.