Add "All available stock at only the default fulfillment site" option to "Stock calculation for orders" setting

At the moment, there are two options for calculating the available stock for the purposes of preventing over-selling. Both of these options allow stock from all sites to be used as the assumption is that stock can be moved between sites to fulfill an order, even if the order (or customer) can only use a single site for the final fulfillment. We know that this sounds slightly counterintuitive, but these options are needed in some situations and also preserve the original functionality from before our recent site updates.

The “Stock calculation for orders” setting, in SettingsOrder/invoice settings, currently looks like this:

This feature request is to add a new option here of “All available stock at only the default fulfillment site”, which can only be chosen if you have picked a “Default fulfillment site”. This would help you to keep stock between two sites separate (e.g. a “Retail” location via a POS integration and another for all your other sales), without the “prevent over-selling stock” feature from thinking it can use stock at your Retail-only site.

This is quite a complex topic, so I hope that I’ve explained this properly, but please do post any questions below if you’re unsure. And if you’d find this useful, please give this a vote with the button in the top-left :smile: