Need VPC for backup server. Have old VPC would like to change. SoP?

Basically gonna vPC two 10Gb ports on our 9K's, 1on A and 1 on B into a VPC.

There is an old vPC from our old UCS that is disconnected. How would I go about changing the VPC? Change the PO interface on each 9k, change the actually single interface on each 9k, or both? Do I need to shut them down first?

What's the best SoP to do this?