Alternatively, they've definitely made changes to onload processing (and list order display) since Ben originally posted about how it works.

That's possible too I suppose.

I often see large groups with the same last name (well, presumably - same first 3 letters anyway) on the upgrade list and have wondered if that is an employee and family. Perhaps this is the example of "non-revs" you were referring to? It's possible that has happened in each occasion where I seemed to jump the queue for PY.

Families are often non-rev, but not always. I've certainly flown in groups of people where there were 3 and 2 with the same last name, all SE.

This is much easier to determine within 24 hours of the flight though. Even AC has challenges going back and looking at past flights.

I've seen myself, while traveling by myself, several names above and below me (about 10 in total) starting with the same first three letters, and a few with the same first initial. So... ¯\_(ツ)_/¯ :)

I believe deadheading employees would be above you, but I wouldn't expect them to have family with them.

I also have a reproducible case to spam the onload list with my name. I can reliably just keep adding a new row with KEN, S :p

Sure, but my point was, seeing similar names can also mean squat. ¯\_(ツ)_/¯
And I never assume I'm the king of the hill (past, present, and even future!) when it comes to these sort of lists, deadheading employees or not... :p
AFAIK, I have never knowingly spammed my name onto the list, unless the "reproducible case" you speak of is spawned by a common task/protocol/[insert whatever word or term you deem appropriate, but you get the gist]...