The main card is the credit card I applied for;

The secondary card is the credit card linked to the main card. The cardholder is different from the cardholder of the main card, that is The main card is you. You can apply for a secondary card for your children, parents, etc. The two cards are of the same nature and type, and the credit limit is the same. If you make a purchase, the consumption limit is also reflected in the main card. card. In short, the relationship between the primary and secondary cards must be the closest relationship. To put it bluntly, two people can use one card for consumption, and one primary card can only be used for two secondary cards at most.

For reference. Please adopt if you are satisfied.