I don't think it's published, and I doubt MM is coded into the upgrade priority on the backend systems. With 1.3M on DL, I'm sure you're familiar with the "features" of DL IT, and that not all DM agents are equally knowledgeable about the intricacies of Skymiles.
Are you
sure that Ms. @
BHammy hit the card waiver - both last year and this year?
It's possible that if you booked you and Ms. @
BHammy's tickets from the same computer, the IP address/Skymiles account was flagged for duplicate tickets (you said they were booked back-to-back and in the same fare class) and your ticket was issued before your wife's - in which case you win the tiebreaker.