I'm booked in for a D class TPE-HKG-YYZ-HKG-TPE, but wanted to upgrade (using miles) the HKG-YYZ-HKG sectors to F only. Does anyone know if it's possible?

Also will CX charge me for a no show HKG-TPE or can I choose to skip the segment altogether? From what I see on CX's ules, you can, but I would like clarification.

Thanks