In my experience, BA and CX don't always see it that way. Both airlines have declined my attempts at a reissue in the past and sent me to another airline.

On the other hand, just this Wednesday CX in HKG handled an emergency reissue for AA on the ticket that I am on now. The CX agent had to send and receive several faxes to AA and spend about an hour on the phone. Two agents worked my case under pressure of a departing flight and got it done. My loyalty to CX just went up a couple of floors.