I am a Cathay Marco Polo Gold Member.

I recently booked a flight in Business Class routing SVG-LHR-HKG-SYD-HKG-LHR-SVG with British Airways, where the HKG-SYD-HKG sectors will be operated by CX (with BA flight numbers).

As they were booked via BA and appear on my booking with BA flight numbers, I cannot book seats for the CX operated sectors. I have even tried to bring the booking up on the Marco Polo site, but it did not bring up seat options as it thinks it is a BA flight. I want to earn BA Executive Club points on this flight as it will bump me up to Silver status, so do not want to attach my Marco Polo Gold card to the booking...

Is there a way I can reserve a seat without having to wait until check in or attach my Marco Polo account to the booking?

Thanks!