How to make AP invoice attachment required before invoice can be save or validated.

Summary

How to make AP invoice attachment required before invoice can be save or validated.

Content

Hi Experts,

We have one requirement in AP invoice to make attachment as a required field whenever an invoice is manually created (not match to PO).

Is there a way we could make the attachment as a required field for AP invoice not match to PO?

Or, is it possible to put a validation and display an error message to prevent invoice in saving or validation if  there is NO attachments?

Or, is it possible to automatically put invoice on-hold if there is no attachments?