Thank you for posting here in the Community, @camckay1.

You can process a Bank Deposit to record your transactions. Let me guide you how.

1. Click on the Plus (+) icon, choose Bank Deposit.
2. On the Add funds to this deposit section, enter the Received from column.
3. On the Account column, choose the Account Receivable for the invoices. As for the payment for an outside party, you can ask for your accountant's advice.
4. On the Amount column, enter the invoice payment amount and the outside party payment amount.
5. Click on Save and Close.

Once done, link the deposit to the customer's invoice.

1. Open the invoice.
2. Click on Receive Payment below the Balance Due.
3. Choose the deposit under the Credits section.
4. Click on Save and Close.

I recommend seeking help from your accountant on how to record the payment of the 13k-worth invoice. This way, he/she can give you the best advice and make sure your books are correct.

Feel free to leave a comment below if you have any other concerns.