Who can we get purchase order to remain open after applying a bill?

I appreciate your posting your purchase order concern here in the Community, Office273.

Let me provide some clarification on how to link your purchase orders to your bill in QuickBooks Online (QBO).

The QuickBooks system allows you to use the purchase order for one transaction. Once you've copied it to a bill, the status will be closed automatically and can't be linked to another entry. You'll have to generate a new purchase order for the rest of your bills. In that way, you'll be able to connect effectively. 

I can perceive the benefit of using a single purchase order for bills that brings several advantages to your business. Rest assured that our Product Development team is working nonstop to enhance our product and deliver the experience for all QuickBooks users. While this feature is unavailable, I recommend sending feedback directly to them. They will carefully consider this option and work towards meeting your business demands accordingly.

Here's how you can send feedback:

1. Click the Gear icon at the top, then Feedback.
2. Enter your comments or product suggestions.
3. Select Next to submit feedback.

You can trace requests for features through the QuickBooks Online Feature Requests website.

After sending the bills with purchase orders, you'll have to record your customer payments. You can utilize this article that entails guidelines about it: Enter and manage bill and bill payments in QuickBooks Online.

Don't hesitate to click the reply button to leave a comment if you have more questions about linking your purchase order to your bill in QBO. I'll be here to assist you at any time. Have a great day ahead!