It's really hard to tell really, since their voices blend so well together.
I see that you have already figured it out bu listening to the surround mix. Good job!
I really like your page and it has been a wonderful effort! It must have been a H-U-G-E task!
A couple of points occurred to me:
-It seems that they didn't have all the master tapes in complete for (or vocal parts thanks to bouncing) so the surround mixes may cheat a bit. They might have only used what they got or Brian could have recorded some additional parts here and there
-You are constantly reffering to some backing part as brian-freddie-roger (from bottom to top). The multi-tracking is of course the key in the big choirs, and the more different voices you got in different parts, the bigger it sounds. So do you suggest that they only did a three-part harmony? Literally, meaning that no double tracking took place? I highly doubt it. On the Bohemian Rhapsody for example the six-part think on "no, no, no, no, no" was most likely done by three of them maybe three times each part even. That measn 3x3x6 is of course 54 or so voices. That doesn't apply to the parts where only Roger was able to sing ofcourse. The last "for me" seems to have only one Roger dominating?
But of course the others couldn't even reach that note and make it ringing as Roger.
Now I really HAVE to invest to my own 5.1 system. I really want to hear all the separate parts indvidually aswell....!
"I'd love to see 70's Queen concerts on DVD!"