You can choose to give them your CX FF number and you will earn Asia Miles. Or give them your QF FF number and you will earn QFF points. Or you can mix it up to suit! Last year I had some Asia Miles about to expire so booked using my CX number, then requested (and got) an upgrade from J to F into CDG. This burnt the last my Asia Miles (had 'moved to QFF). Then, at checkin here in Melb, asked them to take out the CX number and add the QF one. So then got points and SC's credited to my QFF account.....