You cannot transfer miles (as in adding your miles to his so he has more miles to qualify for a free ticket), but you can add him to your account (so he can just use your miles for a free ticket).
From their Terms and conditions:
"You may not transfer or assign your membership to any other individual, trust or estate."
and
"Members may nominate one or more individuals as an "Authorised Account User". An Authorised Account User will be able to make bookings on the member's behalf and redeem miles from the member's account, for themselves, the member or a third party, without the need for confirmation from the Member. The member is deemed to consent to all bookings or redemptions made by the Authorised Account User."
but
"You can hold only one flying club account at any time. Miles cannot be transferred between flying club accounts."
and
"If more than one account number has been assigned to a member in error, the accounts will be combined and the miles transferred to the new single account, less any duplicated bonuses or miles from the same activity."
