I always treat BIAB to RB as a one way street. Everything I can do in BIAB then over to RB for final tweaking. Can't think of anything I'd need to go back to BIAB for that can't be done in RB but I agree the two programs should work seamlessly together and you should be able to go back. But to get BIAB to its current state of capability, with so many added features, it must be quite complicated to go back from RB.