Another idea:
Your friend could start from CAN instead of HKG
CAN-xHKG-LON-ZRH-LON-YYZ-NYC-YYZ-HKG
then later have a 3 segment intra-Asia trip with one stopover, ending in China
or HKG
perhaps
HKG-oDEL-xBKK-HKG or
HKG-oTPE-xNRT-PVG or
your original idea HKG-oDPS-HKG
- maybe with a final add-on HKG-oDPS-xHKG-PEK or anywhere else in China that CX/KA flies to