OBN Invoice without PO

Summary:

Is it possible to process invoice in OBN without PO Number and PO Line Number

Content (required):

We have a requirement that there will be a PO with 1 item line and send to supplier via OBN.

When Supplier sends back the invoice there need to 2 lines

Line 1 for the PO Item line which will be matched to PO

Line 2 for the Misc charges where will be no PO references.

Is it possible to have OBN Invoice processed without PO references ?

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Code Snippet (add any code snippets that support your topic, if applicable):