i would say, GP allows for quasi anything anybody could ever want to do in regards to mixing and routing and switching things around on the fly. (within reasonable numbers vs. channel count )
Point is, you have to understand the audio path, and how to chain modules accordingly, that the necessary switching will work the way you want.
GP is NOT track based. So primarily, you have to create the whole audio path yourself.
By default, there is nothing there. you have to create it.
The routing might look then different than if you would work with a digitale console or so, respectivly how we are used to think vs. real live, dealing with real cables.
Think of this:
in real world, dealing with a patchbay, we would take a cable out of one jack, and patch it in into another = routing A or routing B, you allways have just one cable present.
In GP, you can´t pull a cable.
doing same in GP, both cables would allways be present,
but you would just shut down a volume fader on one channel, and open the volume fader on the other.
so visually, you would have allwass ALL desired routing options (cables) present at the same time in GP.
What you do is just: take volumes down here, and open it up there.
I think, if you grasp this, you have it
For whatever you want to do in regards to switching (complex) routings in GP,
key is here -from my persepctive- to understand what the widgets are,
what they do, and how you can control many functions at once with them.
Rule of thumb is: one widget will allways control just one function at once.
But one HW control can control many widgets at once
i did not understand your exact routing desires…so,…
But it would be strange if you can´t achive exactly what you want.
rerouting 4 stereo audio channels with the flicker of one poti,
would just incorporate that you use several widgets.
simple example:
open Send A, and at the same time return A,
while shutting down send B, and also shutting down return B,
would be a very simple thing to do.
You could go way more complex than this.
you could even incorporate to bypass plugins while switching the Send-return routing for example. ( i do such things in slighlty different contexts)
i repeat:
key is to understand what the widgets are, and how we work with them,
and that you can´t pull cables as such.
the rerouting happens —> based on controlling the audio levels (open here-close there)