Hi Ben
I have limited experience with the 74862 Märklin TT as I use a 7286.
So here is the little I know:
- all tracks permanently powered
- only one detection on the TT itself. More would require quite some changes to the TT (and I don't know them)
- position detection of the bridge. Rocrail needs EITHER (1) a absolute feed back for each of the acces tracks OR (2) a signal deestination reached.
- usually, commands are of in the form of switch commands
- the bridge blocks is made tolerant to ghos trains

Here is my TT 7286, fitted with a two decoder boards from DigitalBahn the DSD2010.
In this case the main decoder is treated like an additional central station
The bridge has been cut into 3 detection zones and the decoder on the bridge reads & transmits those to the layout
A sound module is attached to the bridge as well as ligh signals

In my case the operation is with 48 track mode and to do that I have 2 routes between each access track and the bridge (one to the PLUS side and one to the MINUS side)
The routes and schedules are managed autotaically but the drag and drops works also

Rocrail documentation
https://wiki.rocrail.net/lib/exe...rklin-74862-commands.jpg
https://wiki.rocrail.net/doku.php?id=turntable_generic_en

Cheers
Jean