working on pre-pro for a show with several vmix callers who have to talk to each other on the show. I want to make a "greenroom" where they can all talk to each other before the show.

is my thinking correct in my outline approach:

1. send each vmix call audio to Bus A "Greenroom"
2. return Bus A to each vmix call input
3. when ready to go live, send each vmix call audio to Master
4. return Master audio to each vmix call input

You don't need to change VmixCallAudioSource to Master, you can keep them on Bus A and either send each caller's audio input individually to Master or send Bus A to Master once you push them live. They can all still listen on Bus A while sending to Master.