I have two tickets in two separate PNRs:LHR-HKG on BA (Ticket 1) and transit HKG-SGN on CX (Ticket 2).
I am aware that I have to re-check the bags at HKG for the HKG-SGN legs. My question is: at HKG, can I go to the transfer desks (airside) to check in with CX, then have them collect and check my bags from BA to the flight HKG-SGN on CX? By doing this, I can avoid clearing the customs at HKG to re-check the bags by myself.
I called CX in HongKong and was told that this should be possible. However, the agent sounded not so confident in her answer

Thank you