Not sure if I understand your question correctly?
It is possible to configure vPC between a N7K and N5K in a scenario such that you have two N7Ks which are essentially your vPC peer devices which in turn are uplinked to the same N5K. The physical interfaces on the both N7Ks will be configured as members of a given port-channel group with the identical vPC identifier thus creating the vPC.
The respective interfaces on the N5K will be configured as port-channel members only, and will therefore form an etherchannel with the N7Ks. Neither of the interfaces will have a dependancy on STP as they will be both forwarding.