PROGRESS UPDATE (3/3/22):
Guys, I got slightly bad news. After troubleshooting several potential solutions, it's clear that I simply will not be able to do a 7.1 Mix for this edit. The chief source of that problem is that a Mac's sound-card doesn't have that codec (DTS-HD) installed, and therefore can't process that type of audio properly. In short, trying to change most Mac's sound-card is like trying to sail to Antarctica in a row-boat... in that neither one is gonna happen.
That's also why I haven't been posting in a while, wanted to see if there was a way to solve it first. it just comes down to the fact 7.1 Mixes are designed almost exclusively for high-end computers made solely for that purpose; available only to major editing studios. So it actually seems like MOST editors on this site subsequently have a problem with them, since they most likely have a computer that wasn't designed for 7.1 functionality.
So sadly, it looks like you'll only be getting this edit in a 5.1 Mix...
Sorry guys. I did the best I could /=