When in doubt try to find the answer on YouTube. I have found much better explanations to issues that I have had with Adobe PP on there. You might have to do some searching but it's much better than trying to read through all the attempts to fix the issue through the feeds on your post. I found a great quick video that was PERFECT for what I was needing.
In my video, both my wife and I each wore a DJI wireless microphone. Since I was the only one filming, I still wanted to capture my wife's comments b/c they were priceless for the video.
Check it out here...
https://youtu.be/HmzgcgN6GSk?si=EuRcYwLIa0uoR3gG
Glad to help...and even though your post is from a few years ago, I hope you can add this trick to your creative toolbox.
I cannot wait to use this trick when I upload some of the podcasts I had the opportunity to be on this past year. Some of them had just two people (1 host and 1 guest). However, I have another podcast that I was on that had three people on screen at the same time (1 host and 2 guests).
Randy