Hi @bsr
With ATUM Multi-Inventory this is just possible 'playing' with the settings, but there is no an option to limit the user to buy just from one inventory, unless certain circumstances arise.
For example, if a product has two inventories and one is set in Spain and the other in France, a person who buys from Spain will only see the inventory set in Spain, and the same for the person who buys from France who just will see the inventory set in France ... But inventories are not exclusive under normal conditions. To change this behavior, maybe you could use custom development, but as we don't offer this service you will need to hire a developer.
Best Regards,
Andrea.