This is more complicated than that. Patchmaps are for hardware synths not software ones.

What I'm guessing you want is to be able to have Biab simply substitute ST's sounds for say, the Coyote's sounds using the same GM format. Can't be done. The reasons would take several paragraphs so just accept that.

You have to assign the midi channels to be the same instruments in both programs. It can go either way, keep the Biab channels the same and change the ST ones or vice versa.

And this is only good for one song unless all of your songs use the exact same patch for each instrument. The problem with that is GM only has one Rhodes patch for example while ST might have 10. GM only has one steel string guitar and so forth. Do you really want to be limited to the same patch every time the song calls for a Rhodes? Or, nylon guitar, or anything else? That's the reason people use a big synth like ST, you have all these different instruments to choose from.

That's the good news, the bad news is in order to use all those nice patches in Biab you need to manually set those instruments every time before you hit Play. This is why lots of folks will use a basic GM synth like Forte or the Wavetable just to audition a song, get the arrangement correct and all that then if it's a song you want to keep, switch the synth to ST and customize the patches.

And before you ask, there is very little available in GM synths. Nobody cares about them, they're all basic crappy sounding freebies useful to get you started. There are a couple of good hardware GM synths like a Sonic Cell or Ketron but those cost $4-500. The best deal is Omnisynth from IKM. It's a set of GM sounds for Sampletank and there is a tutorial here about how to "almost" automate it. You might find that in the Tips & Tricks forum.

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.