In C I would route via CPH.

Why:
1. Great timing to PEK, less so from PEK
2. Fairly decent C product
3. Shortest travel time
4. 25% EBG bonus on points, which amounts to quite a bit in C
5. Better transfer airport (CPH vs. MUC and FRA)

An alternative could be to route via HEL, but that would naturally not earn any SK points, but would likely be a faster connection. Have not checked though.