I don't know for certain, but my surmise was that I was knocked down a position at T-120 when the GS CPU window opened, and they remained at the top of the list until departure. At least the #1 pax was not part of a group, since he/she was the only pax of the 3 also listed on the MUC-DEN list. Upgrade was also processed long before arriving to the gate, so not sure how they would have refused if they were all upgraded as a group.