I have AA award ticket for PHX-LAX-HKG with the first segment on AA and the second segment on CX. The CX website says seat selection can begin at check-in 48 hours before the flight, but it also says check in for flights needs to be in order, which would indicate that I can't get a CX seat assignment until I have checked in for the first AA flight, which I believe is only available 24 hours in advance. Is this correct?