Logic Pro: Assign all selected tracks routed to "Stereo Out" to MIX BUS

Hej,
another workflow idea for LPX, that would increase my mix-life greatly:
Select tracks and route every track, that is routed to "Stereo Out" to "MIX BUS" (Bus 1). And ignore all tracks that are already routed to anything else.
Every-time one creates a new track or a new send in Logic it gets routed to Stereo Out. There's nothing one can do about that (at least for Auxes). But I like to work with a dedicated "MIX BUS" and have to route everything to that bus by hand. Maybe someone knows how to accomplish this with SoundFlow?
Cheers
Jan