I'm going to take a stab at it, but someone correct me if I'm wrong...
First, I don't think Pax can be upgrade to Business using their Miles on International flights like they can on domestic flights.
Second, and this is just a guess, the other list of people that showed up were maybe pax from an oversold flight, maybe the day before?!
I'm no non-rev Whiz and don't have the patience for non-revin', especially on Deltoid!