Individual segment selecting credit works only with American Airlines flights. When you advise your travel agent or AA that you wish to segment select your respective flights to several FF program, this is guaranteed to work only on AA flights.

However, it will not work on Cathay Pacific or BA flights.

Worse, if one one airline is checking you through from origin to destination on several oneworld carriers, it will apply the first FF number to all the flights irrespective of what you have booked it under.

The case here is " Cathay Pacific".

I travelled from SIN-HKG on CX. Then HKG-LHR-BUD on BA. The first flight on CX is credited to CX's Asiamiles, and the rest is to be credited to AA. WHen CX checked me in, it automatically put it's CX asiamiles number on all my boarding pass. When I protested, they told me that they cannot 'split' the FF number out. I had to recheck in at HKG in order to get it done properly.

You have all been warned!