implement multi-card household management. According to Douding. com, Party A implements multi-card household management for credit cards, and all cards (including supplementary cards of the main card) under the cardholder's name belong to the same credit card account. Both the main card holder and the supplementary card holder with full capacity for civil conduct promise to be jointly and severally liable for all debts incurred under the main card and the supplementary card, while the supplementary card holder with limited capacity for civil conduct is only liable for debts incurred under the supplementary card.