I have an insight here and would like to give you a sharing.

I have been a DM for a few years and I always handled my CX booking directly with official CX channel, not OTA.
Once, last year, I had to fly to Harbin but it was not a CX port. I booked the CA tkt at trip.com and eventually I checked thru at HKIA with my CX tkt to PEK, connected to CA tkt.
I input my CX DM membership when making the booking at trip.com. When I chked in at HKIA, I realised there was a mbrship number I have never seen on the CA bp and I asked the staff to remove it.

The staff said this is seen quite commonly when booked with mainland OTA - can be a possible fruad that 'someone' is creating faked FFP account and link to the booking - then use the reclaimed miles if someone is not familiar with the FFP issue or does not even care about FFP mileage...