I added a few Amex additional cardholders over the phone with a telephone rep, and provided birthdates for them (but not SS#s). Since then, I've been receiving a steady stream of emails and letters in the mail from Amex, notifying me that I need to provide them with the missing SS#s for the additional cardholders in my account.
If I don't provide Amex with this information (and I don't see any reason why I should), is there any additional action that I should expect from Amex, other than this continuing stream of annoying emails and letters? Will they ever stop asking me for this information? Is there anything else that they will do when they realize they're not getting any response?
Why does Amex even insist on this information, if I'm on the hook for my additional cardholders' charges anyway? Are they simply being opportunistic? I would think that they would have a pretty weak claim (for unpaid charges) against an additional cardholder anyway, considering that the additional cardholder never applied for the card, or explicity agreed to any terms.