I was told by a couple Citi CSRs that if you have a checking / savings account you can link all of the various Citi cards to them. Otherwise you can only link same branded cards ex AA can link both AMEX and VISA. Otherwise even though the login page is the same you have different logins. I currently have 3 separate accounts (AA, HH & TY) since I do not have a bank account with Citi.