Hi MrMiyagi,
It's good to hear you were able to record the loan amount in QuickBooks. Loan amounts are usually track under liability accounts, since we're unable to use them in paying the invoice directly. You can create a journal entry to use the loaned amount to pay the invoice. I'd suggest contacting your accountant for additional guidance on what account to use to not mess up your books.
One of them will be able to assist you further with the best account to use to reduce the liability correctly. Also, please know that we can't suggest which account you should select in this type of situation.
Additionally, I recommend the following resource about creating a journal entry: Create a journal entry in QuickBooks Online.
Please let me know if you have any additional questions. I'm always willing to assist.
