The award ticket is linked to the FB account used to book it. There is no need (and no way IMO) to enter your own FB number in this booking, as you cannot earn miles for this trip. If you want to access your booking on-line, you can access it with the PNR numer or the e-ticket number + your name.

For the 2nd part of your post, this is obviously a kind of computer glitch but pretty embarrassing. It means that you can access your relative's account even without having to enter his/her P.I.N.