My 2 college age sons will be doing some traveling this summer and could benefit from the first checked bag free as Amex cardholders. They both have cards under my account but since I won't be with them I don't think they would qualify for this as the rules state "Primary Cardholder". Will showing their card (Gold Amex-secondary under my account) waive the fee for them? Or do I need to have them open their own account- and if so does anyone know of any better enrollment bonuses (or possibly referral bonuses) than the one offered on delta.com (20,000 plus 5,000 for additional cardholder)?