Is it possible to set up and manage stock in Craft Commerce even if a product stock goes into the negative? The current commerce project I'm working on is open to the public so anyone can add items to a cart but only registered and approved members will have the ability to submit carts as orders. What I would like to be able to do is keep out of stock products available in the store so that they can be added to carts and orders. The orders are manually processed so an out of stock item just means that further production is needed. Tracking negative stock would also help guide production because it would give insight into how many of a given product is needed at any given moment in time.
Commerce does not have a back-ordering (negative stock) counter at the moment. To allow ordering of more items that you have on hand, you would need to either:
1) enable the 'unlimited stock' option on the variant which would not track the stock and allow orders of an unlimited number of variants.
2) Choose an arbitrarily high stock count to allow ordering above what you have on hand. For example, if you have 32 items on hand, make the stock value 2032, allowing for the stock to drop below 2000 would let you know the number of back-orders.
Either of these might not be ideal.
A third option could be using option 1 with a plugin that listens to the
onOrderVariant event and updating your own stock counter within your own database tables.
We hope to have features like back-ordering in future versions of Craft Commerce, and you can vote for such features here: https://craftcms.uservoice.com/forums/295386-commerce/suggestions/7817436-pos-and-inventory-management
Hope that helps.