You can apply User Permission on item on the link fields like Item Group, Brand Warehouse etc. As per the standard permissions, if user has read permission on the Item, then in the Sales Invoice, User will be able to search and select all those items, even if that item is not available in that Warehouse.
Are you also making Delivery Entry from the Sales Invoice? If yes, then if stock if item is not available in the Warehouse, then user will not be able to submit that Sales Invoice.
This is scenario , i wanted do:
i have 11 retail branch, each branch have their own stock. [i already linked each branch with their own warehouse].
All this retail branch have employee (user), but all this user might switch branch location, i want create something easier for them to do choose for sale invoice items based on the attendance of their branch selected. is it possible ? or any advice how should to erpNext to get this aim ?