Hello,
Okay, you're reading me but I'm not sure that you want to accept my answer :
You can't have an order item with a quantity inferior (or equal) than zero ; it will remove the product from the order.
That's why I mentioned to put a product with a free price.
You can open another thread in HikaShop forum section for your request but I'm afraid that I already gave you the fact : you can't have a negative value and you never will be able to do so.
It's just not compatible with the HikaShop structure so there is not way to have that behavior.
If you want to do what you want to do, you need to create fake order items with "refund product A" and a "0" price.
So you will keep an entry in the order that the "product A" was there before and that item has been removed.
Nothing less, nothing more :
Until that ; you can edit item in the order. So you can change the price, the quantity and the name.
You can even remove the product and place a "virtual" product instead.
The customer buy 3 items and what to return one : you change the quantity.
The customer want to return full item : you remove it from the order to perform a restock and you insert the "virtual" free product.
Afterwards if you want to do a feature request for HikaShop, you can but it will be rejected due to the impossibility of implementation ; and that's not how it will be handle in the future, when we will have the time to work on the "partial order status" feature.
For the moment there is no "order status" per order item, but that is something I started to implement when I worked on HikaShop 3.
I can't provide any schedule or else for the moment ; but that's the kind of feature I want to provide in the future.
Regards,