Let's revisit the "casino solution." which is a more basic system to manage the single track section. The basic circuit is on the right, and the modified one below it.
I added the Home and starter signals. There is no interlocking, and thus they are fully manual. Their main purpose is for the staion operatoir to show a mainline driver when to come in or lave the yard. it means for Grattoen and Costerfield they manage the "virtual staff". all other locations are managed by the mainline operators.
Because the staging yards are unmodelled, they do not have signals, just the "virtual staff"
This shows the entire mainline. Ninamanina could also be done.
Since Hazeldale Loop is rarely used I propose to switch it out. This would combine both section into a super section. When switched in the section works normally. Operators run the hazeldale as thry do now. But when switched out it is Costerfield and Graytoen operators who run it.
Here's a diagram how the "virtual staff" works.
Important to remember the section is defined as being between both Home signals. If the Home signal at your destination is set at Red a train has to wait at the home to enter a station andcan only enter when a proceed aspect is given.
As said before Graytown could have this system for the main and the branch. It is quite flexible. You could even have one for the mill branch at Costerfield.