As a 1K, I have been watching very closely for a few weeks the First Class booking status & listed initials for upgraded passengers on the Upgraded list (using the tool I found here on FT months ago) for a 2-cabin domestic flight on which I have tickets for 2. R & RN has fluctuated greatly between 9 and 3, always the same number for both buckets, several times during those weeks as Revenue Management changed them.

At the 72 hr time window slot, which is the beginning of the window for Complimentary Upgrades for 1Ks, I watched my email and the booking status & listed upgraded initials for passengers every few minutes. One hour and 45 minutes into the window I got the Complimentary Upgrades for myself and companion and I immediately checked the First Class booking status and listed passengers. 5 passengers were added to the upgraded list at the same time of the CPU sweep, the R & RN numbers both dropped by 5 from 7 to 2. Booked First Class #s increased by 5.

I think I have read elsewhere in this Forum that CPUs do not come from the R bucket (or that existence of R does not mean CPUs will be given). In the example I have just given it appears that a sweep with R>2 will exactly take
from the R bucket(R shows on my tickets after a CPU).

By the way, I had relatives who also booked for this flight in First on Standard Award JN mileage tickets. Their initials appeared on the upgraded list a few weeks ago. When Saver Award tickets became available for the flight, they switched to IN tickets. Their initials disappeared from the upgraded list, but their tickets were reflected in the "booked" number.

Besides Standard award JN tickets and CPUs, from what other fare buckets will cause person's initials to show up on the upgraded list?

As a side note, R/RN has since remained at 2 between 72-48 hrs, F5, 6 seats show on map, 18 booked in First with 24 total seats.