I know this isn’t exactly what you have been looking for, but I have created three talkback mic options on each of my scenes to go to different destinations:
I’ve had some luck with using channels 38, 39 and 40 (since they were unused channels) and assigning their inputs to “talk”. Then these channels are sent only to specific monitor aux outputs. I assign those channels to seldom used layer, and faders set to unity and muted so they are ready to go.
When I want to talk to the drummer, I disengage the mute button on channel 40 “DrmsTB” and speak into the talkback mic. I don’t even have to push that standard talkback mic button on the surface. So far, having three talkback mic destination options per scene is working well on most of my scenes, with two exceptions that I haven’t quite figured out yet. User error I’m sure. Other than that, it seems to work well for me.
Hopefully that will be useful for you.