Forget it. The supplementary credit card is handled by the principal cardholder for the supplementary cardholder. It is linked to the account under the name of the principal cardholder and has the same limit. After the supplementary card consumes, it will be accounted into the main card account. The supplementary cardholder can repay the supplementary card separately. , or the principal cardholder can repay the money directly to the principal card, so it is counted as the principal cardholder's credit.