Essent Preorder Back in Stock

As a pre-order app, it does the trick. When you have 0 stock in all your locations, it allows you to pay and order a product ahead of time.

The problem with this is, that when you have multiple locations, dark/online store and physical stores it takes ALL location inventory into account, which limits the pre-order functionality and defeats the whole purpose.
How do we get the app to read separate locations or allow it access to only specific locations for inventory levels.