You have 2 elderly relatives (?) who want to join BAEC and have a trip coming up that they'd like to use to start collecting TPs and miles. ^
Why not sign them up as a favour to them, and as they don't have Internet or email, (and as they may become confused by all the mailings etc they get) then surely it's easier for you to administer their accounts on their behalf. You may as well also add them to your HHA and all pool miles together.