Recognize commission at the same time as revenue

I do dropshipping and every transaction comes with a fixed % commission. How can I make the commission expense be recognized at the same time as the sales revenue in Manager? Do I need to create a separate purchase invoice?

Your post is fairly vague. Do you do dropshipping for someone else? Or does someone else do dropshipping for you? Who is receiving the commission? Who is paying the commission? Who are the customer and supplier in all relevant transactions? Has anyone sent you a sales invoice requesting payment for dropshipping services? If you want help, you really need to describe the circumstances completely.