Originally Posted by emcampbe

So, my recent experience on this with an upcoming itinerary that is a mix of AC/NH/UA segments, all marketed as AC except for one NH marketed leg, is that I was able to use the Amadeus PNR (which is what AC uses), and when I typed it in, UA was able to pull it up, and displayed the UA PNR (I could not find a UA PNR on the AC site). I had to do this because even though I booked with my MP number on the itinerary, somehow, that didn't transfer over to the United PNR, which is why it didn't auto-populate in my MP account, like it should have (also explained why it was trying to charge me to select preferred seats on the UA segment, when I should have those for free due to my silver status).