I was just thinking about this, but i think the best solution for ABCBA is to require either B or C to be a hub.
For Example my hubs are say JFK and LAX. I fly JFK-LAX, LAX-SEA, SEA-LAX, LAX-JFK. This way, aircraft can flow through your network and not just in and out of the hub they are based at. It also allows you to utilize your aircraft better and to better serve your markets. Or you could fly JFK-SEA, SEA-LAX, LAX-SEA, SEA-JFK. Both ways have the flights going to hubs with the same aircraft.
This is the case in RW, Aircraft arent typically stationed at specific hubs just because, if they are there are specific reasons (SWA's 737-800's at EWR or American Eagle's ATRs in TJSJ(safety reasons)).