Hi TomManley,

Welcome to Community!  It's great to hear that your client is utilizing the banking function to easily update their transactions from TD and keep their records up to date.  In QuickBooks Online linking the accounts can be done without complication.  However, in this situation you wouldn't be able to link a line of credit.  However, you can create a new account in the chart of accounts and then manually upload transactions in csv format.  I'd recommend reaching out to an associate for their insight on setting up the account to ensure the transactions hit the books correctly.

If you have any other questions or concerns, please feel free to reach back out.  We'd be glad to help!