This open source POS version only supports Default Stock. It means all locations (that link with the POS you created) can only link to one default stock. All your stores using POS will share the same inventory in one warehouse.
To use multiple stock for different warehouses and stores (omnichannel solution), please upgrade to our Commerce plan.
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Go to POS > Manage locations > Edit a location. And then scroll down to Stock Selection section, choose the stock (warehouse) you want.
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Save the POS Location information. The POS machines in that Location will display all items in the Default stockchosen stock.