Does anyone know the algorithm used by UA for 1K complimentary domestic upgrades? Here's the situation: my wife and I are both 1K and had a trip planned with our daughter who does not have status. We had expected an upgrade (we almost always did on that route), but did not. Turns out that we lost our status by having our daughter on the same itinerary: If a reservation includes three or more travelers, and only one is not a Premier member, the Complimentary Premier Upgrades will be processed according to the lowest Premier status level in the reservation. If two or more travelers on the reservation are not Premier members, it will not be processed automatically. In these cases, Premier members should call the Premier Priority Desk to request a separate reservation for themselves and the eligible companion. source: https://pss.united.com/web/en-US/content/mileageplus/premier/upgrades.aspx Bizarre policy for sure, but I thought that once we knew the rules I could adjust for it. So for our trip this weekend (also with our daughter) I did exactly as they recommended ... I split the itinerary into two: one for me alone, one for my wife and daughter. The 96-hour window arrived, five upgrades were granted (have never seen that many on this route); but we were not one of them. So I called United: The first representative claimed we didn't get the upgrade because I had split the reservation and we lost our priority. The second representative claimed that it was a highly complex computer algorithm and if we didn't receive an upgrade it's because we don't fit the upgrade criteria ... whatever that means! Haven't tried for a third explanation. So I'm wondering if anyone knows how complimentary upgrades are determined (IOW how the algorithm works); or is it just part of the merger mess?