The number of zonal interchange points here seems to be inconsistent here.
For example, for the Bombay-Madras trunk route, currently there are only 2 zonal interchanges required: CR-SCR at Wadi, SCR-SR after RU. At Hotgi and Gulbarga, the interchanges are only required for trains going towards Gadag and Bidar respectively, not for the trunk line. So, they should not be counted.
After formation of SCoR, this would increase to 3. (CR-SCR at Wadi, SCR-SCoR after RC and SCoR-SR after RU). Even if Gulbarga division is formed and transferred to SWR, it will still...
more... require 3 interchanges only (CR-SWR at Hotgi, SWR-SCoR at RC and SCoR-SR after RU). So, it won;t make any difference for Bombay-Madras route if GR is in SWR or SCR after SCoR is formed.
But if Hotgi-RC is transferred to SWR after formation of SCoR, then it will create more interchanges for SC-SBC route - (SCR-SWR at Wadi, SWR-SCoR at RC, SCoR-SWR at DMM) compared to the present arrangement (Wadi-RC in SCR) - which will need only 2 interchanges - SCR-SCoR at RC and SCoR-SWR at DMM.
A simpler solution, if all this mess of reorganization is carried out, would be to just transfer the Wadi-GR section to SCR so that no zonal interchange is required for trains going from Bidar to Raichur via Gulbarga. Even earlier, Wadi-Raichur used to be under CR, but it was transferred to SCR to remove the zonal interchange for GTL-SC trains.
This way, the number of interchanges required for Bombay-Madras, Bombay-Bangalore, Bombay-Hyderabad and Hyderabad-Bangalore will be minimum, while also removing the interchange required for GR-BIDR route.