Hey Jackieholmes,
Welcome to the community page and thank you for your question. With ANY contra entries, we will always advise you to speak to an accountant about the best way of doing this for your account.
There are a few ways of showing contra, but i think we can possibly avoid going down the route of journal entries by utilising the "Cash at Bank or in hand" account, and selecting that account when you create the payment for your invoice. When you then create your expense, you also select the bank account as the cash at hand account for the (smaller) expense.
This would also be accurate for what occurred in real life; while there is no specific link between the transactions, with having the same date for the invoice payment and the expense, they will appear side by side in the reports.
Let me know if that helps at all, or if you have any questions.
