Note also the OP keeps referring to companionS, however specifically mentions that they split the reservation immediately after applying the instruments "to increase the likelihood of upgrades clearing." (So essentially created a PNR of OP + 1 companion.) WineCountry, perhaps you can provide anecdotal experience but wouldn't the OP's splitting of the initial reservation into 2 + 2 cause the two non-status passengers to lose the 1K upgrade priority, or does the fact that an instrument transaction simply took place while all four passengers were on the same initial PNR with "ghost" 1K status cause the 1K priority to become embedded in the instrument upgrade request and maintain after the split. I do not have experience with instruments but with the CPU, where I was traveling with a companion and I split the reservation after the CPU window (and the PNR showed the "CPU requested" icon) but before check-in and my non-status companion went on the Upgrade Standby List (and even ended up getting upgraded at the airport), which tells me that after the computer flipped the "CPU requested" switch that computer coding for my status became embedded in my companion's individual ticket and exclusive of mine. My assumption is that had I split the PNR prior to the upgrade window the outcome would have been different because there was no transaction to trigger attaching my status to my companion's ticket.

SAP