Consumers holding American Express charge cards now can set spending limits and alerts on additional cards tied to their accounts, American Express Co. announced today. Each additional card has a distinct number, so if one card gets stolen or compromised, other cards tied to the master account do not have to be reissued, according to AmEx. AmEx during the past couple of years has quietly enabled secondary consumer charge cardholders older than 18 to build credit histories based on how they manage the cards tied to primary accounts, an AmEx spokesperson tells CardLine. Now primary consumer charge accountholders can sign up to receive e-mail or mobile text alerts when set spending limits on secondary cards are approaching or have been reached, and AmEx is separating spending for each card on bills sent to the primary cardholder. Primary accountholders can change spending limits online or by phone, and changes will affect secondary cards within minutes, the AmEx spokesperson says. All cards tied to a primary account build a pool of reward points for the primary accountholder, she adds.