Using Air France flyingblue miles, I have a flight booked on WestJet for two people on the same reservation.

Is it at all possible to cancel just one person from this reservation without impacting the other one? I don't want to do a full cancel and then rebook the one passenger because there's no chance I'll get the same fare back.

I can't find a way to do this online, so before I spend a lot of time on the phone wanted to know if its even possible.