You can assign a warehouse to only one branch.
By default, warehouses that exist before you enable the multiple branches feature are automatically assigned to the main branch.
From the SAP Business One Main Menu, choose
.In the Warehouses — Setup window, find the warehouses you want to assign or specify a new warehouse code.
On the General tab, from the Branch dropdown list, select a branch.
Choose the Update or Add pushbutton.
You can use a branch in transactions only if the selected warehouse is assigned to the branch.
You cannot reassign a warehouse to another branch when it is used in any open document. You can reassign a warehouse to another branch when it is used in only closed documents.