Hi Mark,
I see the benefit of including PO numbers on each line item on an invoice. However, this is currently not a feature in QBO. As a workaround, you'll want to manually enter them in the Description field.
I'm sure many users will like this option as well. I'm encouraging you to submit feedback so our product development team can consider adding it in future updates. Just click on the Gear icon and choose Feedback.
If you like checking references for QuickBooks Online, you can go to the main support page and choose the said product. You can also utilize the QBO test drive to explore new features.
We're just right here if you have other concerns with QuickBooks Online.
