Hello @hql,
While developing plugins, we have chosen to follow GAAP (Generally Accepted Accounting Principles) which states that administrative changes should be documented separately. This means that an original invoice should never be modified by a refund. In most countries (at least in the EU) this is even considered fraudulent (and illegal).
Our Professional extension provides this separate document for refunds – the Credit Note, as well as a feature to deduct refunded items from the Packing Slip.
We have chosen to keep all Refund-related features of our plugin in our Professional extension.
Here’s an example of an order where one item was fully refunded and another was partially refunded:
When the option to subtract refunded quantities is then enabled:
It only shows the remaining items/quantities:
If you have any further questions about this, please send an email to [email protected] – support for paid software is forbidden in these forums. 🙂