I'd be glad to help you import all charges for 7 cards into QuickBooks Online. Before setting them up, check with your bank first and see how they send the downloaded transactions. If the transactions are downloaded to one account, connect only the parent account.
However, if they are imported to the individual accounts, you can add the 7 cards as sub-accounts to the parent account and link them.
Here's how to add a sub-account:
Go to Accounting on the left panel.
Under Your Company, choose Chart of Accounts.
Click on the New button.
Under Account Type, select Credit Card.
In the Detail Type drop-down, select the type of account you want to create.
Enter the name of the account in the Name field.
Mark the box for Is sub-account.
Click on Save and Close.
To learn more about setting up parent, sub-accounts and connecting them into online banking, see the recommended articles below: