The client I am working with has a requirement that they are able to give credit memos before either full or partial capture of an invoice (i.e. money is authorized but not paid).
The idea being that no stock is being managed by magento, and magento has no way of knowing if something is in stock at a given time. The stock is managed by a 3rd party system. Generally they will receive new stock within days, but it may not necessarily match the items ordered. They want to be able to refund a part of any order.
Is there any way of doing this? Are there any extensions that offer this functionality?
The other way to look at it is, we need to be able to amend an order after its been authorized. In order to adjust the amount of money that is taken from the customer, specifically omitting any unavailable items. This must appear to be a refund from the customer's perspective as per our client's requirements.
All of this will be managed using a 3rd party integration that leverages the Magento API.