Hi,

Please refer to the following, 

* https://www.odoo.com/documentation/18.0/applications/finance/accounting/customer_invoices/electronic_invoicing.html

Hope it helps

Goal:

You want to register a vendor bill, link it to an existing PO, but avoid auto-filling the invoice lines based on the PO lines.

How to do it in Odoo (Steps):

1. Receive or Upload the Electronic Invoice

If you’re using the Electronic Invoicing module (for example: PEPPOL, FatturaPA, etc.), Odoo will create a draft vendor bill.

2. Open the Vendor Bill:

Go to:

[Open Draft Bill]

3. Manually Link the Purchase Order

On the vendor bill form:

• Find the “Auto-complete” field labeled:
  "Add Purchase Order"
• Select the related PO, but do not click “Add Lines” when prompted.

That step is optional — you can select the PO without importing the PO lines.

4. Enter the Invoice Lines Manually

Instead of using PO product lines:

• Manually add invoice lines from the e-invoice (matching the vendor’s format or document)
• This is useful if:
  • The invoice is summarized
  • The PO contains more detail than the vendor invoice
  • You want to use different accounts or custom lines

Tip: Keep the PO link for reference/audit

Even if you don’t import the PO lines, the link between the Bill and the PO allows:

• Matching for validation
• PO/Bill comparison
• Payment matching