Booked ORD-SFO in economy with 1 companion (silver). I am platinum and we are #1, #2 on CPU list with 10/16 booked. We are seated together in economy+. There are no open 'rows' left in first, just single aisles or windows. How will UA handle the CPU's? Will we get skipped over if they release seats 1 at a time? What if they don't release seats 1 at a time, the seat map remains the same and therefore we cannot sit together? What will UA do then?

Pre-checking in, if on a common PNR, you will be treated as a party of two and will need to clear together.
Once you check-in, you will be asked if you wish to remain on the waitlist, if so, your PNR will be split into separate PNRs and can clear individually. You can wait to check-in until you get to the airport to check-in that will not affect your early CPU chance. If you have not cleared until you get to the gate, you can tell the GA you only want to clear if both can clear.
Your companion will maintain your status if you do split the PNR.
UA will clear you into available seats and will not move others to provide adjacent seats.

Thanks for the reply and follow up discussion. Just to be clear - what gives us both the best chance of getting upgraded? Splitting at T-24, waiting as long as possible to check-in and split, or not splitting at all? I am wondering if splitting the PNR will drop her down a few spots since she will clear as the 'last platinum.' First class cabin is now 13/16 booked. Still sitting #1,2. What would you do in this situation?

Our plan, if upgraded was to ask our seat mates to swap. If that doesn't pan out, we are perfectly fine sitting by ourselves. I am not a DYKWIA!!

which is more important? -- getting at least 1 upgrade (then split) or only getting both upgrade (all or nothing) -- stay on a common PNR as long as possible

No, will stay at your priority
No looking good

If the upgrades come through for both, given that seat map seems like you'd have a good chance to persuade someone to switch aisle seats and end up together. I wouldn't worry too much about that . . .

T-24 hit, I split the PNR at check-in. 10 minutes later only I received an upgrade. Companion stuck at #1 on the list with 2 seats left. 15 minutes later cabin was filled. Companion still in Y. Looks like I'll be giving up my seat for my silver companion

Hope you can grab the aisle seat (or the upgrade came from the middle).

Yes, have my own row. I made sure to place myself in the middle seat and her in the aisle just in case the plane was full and only one of us gets the CPU.

Does anyone have any recent data points on this issue? I have a flight this Friday where my companion and I wound up with split records on the outbound, as upgrade hadn't cleared by check-in, and now he's not showing on the upgrade list for Friday. I called the 1K desk, and they told me all I can do is ask the gate agent for help, but by that time, everyone else will have leapfrogged him for the upgrade. This really is a silly system of having to be in the same record to upgrade a companion. WIth AA, you can designate any one pax on the flight as a companion to have your status for upgrade.

I had the same problem as you last month.

I was Platinum, my sister with no status was my only companion. No CPUs happened before check in, so we didn't check in until we got to the bag drop, where I selected to split the PNR for upgrades. I was upgraded at the gate and my sister immediately dropped off the upgrade list. The GA had to re-add her and printed her new ticket immediately. She also wasn't on the list for the return. Agent at the check in counter manually re-added her, but she didn't snag the upgrade.

The agent on the phone said it was a known bug, apologized, and submitted a report.

I had a similar event last week.

I used miles to waitlist to FC for myself (I was only Silver and only just made Gold during the trip) and wife (no status) on our DEN-LAX-HNL flight. I do also hold a UAC card and have high spend on it. We cleared and the PNR split (or so I've been told). She did drop off my app. I'm uncertain if that's because she used her phone or the upgrade but believe the upgrade.

Concerned about her getting left off and leapfrogged on the return HNL-SFO-DEN, I called. Twice. I was told only the gate agent could fix it. I knew we wouldn't make it to the front on the HNL-SFO as it was nearly full even though I made Gold during the trip. Don't laugh. Gold is huge for me and my usual 15 work flights/year. ;-)

After check-in, I cleared SFO-DEN. Shortly after, she popped up on the upgrade list HNL-SFO further down from me. I was 8, she 15. 22 total. She did not appear on the SFO-DEN list. Sometime prior to the flight, she suddenly cleared SFO-DEN.

Strange but it seems the phone agents don't really know how this works.

Not that strange. Almost no Reservations Sales Representatives (RSRs) have worked in a gate agent capacity as Customer Service Representatives (CSRs).

The RSRs have more expertise in fares and their rules, and program policies, rather than the operational details CSRs see daily.

3 passengers on the reservation, two 1Ks and one no-status. It's a two-segment trip. At T-96, the first segment is full in F, the second has plenty of PZ. Do I understand correctly that nobody on this PNR will be upgraded on the second segment unless it's split? And the only way to split before check-in is to call, since the "separate traveler" button is gone from the website?

In the past UA stated the following, can not find it on the present website -- are you showing as CPU eligible?
more in Comprehensive Companion CPU Questions

Showing as "CPU requested" as of now. Looks like some upgrades were processed at T-96, and it went to PZ0 for the time being.

The language about "three or more travelers, and only one is not a Premier member" is still on the UA website:

https://www.united.com/ual/en/us/fly...ponsoring.html