One of my VIRB Elites has died. Of course since they have been out of manufacture for years, replacing it in kind seems to be out of the question. What is the possibility of getting a GoPro and having video in video work with it and my remaining VIRB Elite?
I haven't tried it with a VIRB Elite but I'm pretty sure it worked for me with one of my VIRB Ultra 30s and a GoPro. If it doesn't work for you in VIRB Edit, it probably will in DaVinci Resolve or Shotcut (both free and very good).
If you can't turn them on together and facing at something like a wrist watch to manually sync the two videos, then turn them on then shot video of the watch with one cam for a few seconds and then with the other cam. Then back at home trim the start of each video so that they both start at the same real time. You might be off by a few frames but only a fraction of a second if you're careful. After that, PiP and other synchronized editing should be easy. Good luck.
Will give it a shot and see how it works out.