Just report back my experience. No one could do it. After I attempted (but did not finish) the OLCI, all segments FFP# changed to my AS #. There is no option for multiple FFP# on OLCI interface.

I then asked the check-in agent at LAX to enter the MPC# for the KA flight. He tried a few minutes without success. All my BP still shows AS#. At HKG, I asked the gate agent to do that same thing. He tried, and again, his system won't allow him to do that.

I will not even try OLCI on my returning flights and see if both numbers will be in place. (My reservation shows AS# for CX flight, and MPC# for KA flight).