Thanks for joining the thread.

In QuickBooks Online (QBO), we can receive only part of a purchase order, or make a partial payment and add just those parts to a bill or expense. This links multiple transactions to the same purchase order. You can also link multiple transactions to a single purchase order.

QuickBooks Online automatically closes purchase orders when all quantities are added to bills, expenses, or checks. You can check out this article for the steps and details: Add purchase orders to expenses, bills, or checks in QuickBooks Online. Then, go to Add part of a purchase order to an expense, bill, or check section. 

However, the option to receive only 1 line item only in the Purchase Order without bringing over the entire items is unavailable in QBO. We see consumer feedback as an opportunity to improve the numerous features of our products. I'd recommend giving our engineers direct feedback. They may look into this suggestion and incorporate it into future updates. Here's how: 

1. Go to the Gear icon on the top menu.
2. Click Feedback.
3. Type in your recommendation in the Share your feedback field.
4. Tap Next.
5. Follow the on-screen instructions to complete the process.

I've attached screenshots below for your reference:

Also, I'm adding this article for additional information, as well as the steps for adding a part of a PO to a transaction as well as updating its status: Enable and use Purchase Orders in QuickBooks Online.

Please keep in touch with me here should you need any further assistance regarding managing your POs or have follow-up concerns about QuickBooks. The Community and I always have your back. Have a great day ahead.