Very strange CO/UA split trip happenings

I recently took a trip that went SEA-IAH-PBI/FLL-DEN-SEA

It was booked via CO, but the last leg (and only the last leg) was on UA. The return trip took place on Friday. Perhaps irrelevant (perhaps not), FLL-DEN was delayed an hour, and DEN-SEA was also delayed an hour.

Also perhaps irrelevant (perhaps not), there were 4 of us, 2 CO Gold (wife and me), and 2 Non-Elite (our kids). I upgraded the kids with miles (only applied to the CO FLL-DEN leg), and the wife and I were EUAed *all the way through*. This surprised me, as I didn't expect the UA leg to actually perform an EUA.

Our PNRs were all split, as when I booked this, I wasn't sure how I would work the upgrades.

Yesterday, the wife and I got check-in reminders for a UX flight DEN-SEA *today*! I checked the kids' PNRs and they are now booked DEN-SEA on UX on *Tuesday*! I just got a trip alert from CO, as well.

So what do you think happened here? Why would they think our last leg had to be rebooked, when we already traveled? Is there anything fun I can do with this? When I try to check-in or assign seats, the website gets very confused and says it can't find the ticket.

What do you think the odds are that we'll get credit for the leg we already flew DEN-SEA??

 

Sounds like because of the delay, you were auto-protected on a different flight. That happens all the time. Once you make the original flight, the system usually does not cancel your "protection" flights, so you'll get alert reminders. This is always fun during a MR when you have 7 or 8 segments, then get re-booked a couple times. I see UA easy update alerts for all original plus re-booked flights and just ignore them cuz there are so many!

You will get mileage credit for what you actually flew (your original flights) and nothing will come of the re-booked protected flights.

 

Not unexpected during irrops when an automatic rebook happens. Actually, it doesn't even mean that you held confirmed space on the flights that you didn't take. Sometimes those flights are still present in the PNR and will trigger alerts, even though the ticket has been fully used. Bottom line: it's weird, but it doesn't matter