As the name implies, one is the main card and the other is the supplementary card, which is generally used by family members (wives or children) \ x0d \ x0d \ All debts incurred by the cardholder when using the credit card are borne by the cardholder of the main card, and the cardholder of the main card directly performs the debts to the card issuer or special unit. Therefore, the principal cardholder and the deputy cardholder are mostly related to property, or know and trust each other. \x0d\ In the relationship between primary and secondary cardholders, the primary cardholder is in a dominant position and has the right to decide to add or cancel secondary cards, while the secondary cardholder is in a subordinate position. If the primary card is cancelled, the secondary card should be returned to the card issuer voluntarily. When the main cardholder requests to stop using the supplementary card midway, he should also return the supplementary card to the card issuer, and the outstanding debt will still be borne by the main cardholder.