One thing you might check out is an app called "acapella". Very slick, and makes it really easy to create collaborative videos. Since everyone records into the same app, you shouldn't have these issues. You give up a lot of flexibility compared to using a full video editor, but it makes things incredibly easy, and might help you avoid these issues.
Here's a rough 30 second test I did a few days ago. The whole video took about 3 minutes to put together, push save, and it's done. I did all three videos, but you can bounce it between people and have different players add their parts, each in their own part of the screen.
https://mixcord.co/acapella/p/JXppsHZywqRmxu3kLdwVuA/
if you look around, you can find some pretty amazing videos done with this, with entire choirs, orchestras, etc.