What lkrt meant is that at least for those cases where both marketing and operating carrier uses Amadeus, there are no longer multiple, carrier specific reservation numbers.

In the past for a CX marketed, but AY, CX and KA operated itinerary, I had 3 separate PNRs to manage my bookings at each airline. Since April, AY updated their system and there is only one PNR, regardless of the number of carriers involved. This supposed to make things easier, since you as a customer would not have to jump through hoops and loops just to find the "right" PNR.

Of course, IRL, at least for now this just doesn't work. With the single PNR you in most cases (?) are not able to do seat selection on AY's site for flights operated by other carriers, nor can you use that PNR to log in to other carriers' site to manage your booking there...

So far this seems to be a great enhancement. #Sarcasm

With AY and AA using different GDS, there is likely a separate PNR existing, but seems like that since this upgrade all codeshare flights are a bit messed up.