Start with location-level truth
Every unit should belong to a warehouse or a store. If Accra and Kumasi share a single quantity, you cannot replenish either branch with confidence.
Make transfers a workflow
A WhatsApp request is not a stock movement. Requisition, dispatch and receive should change on-hand quantities with a reference you can audit.
Let POS close the loop
Store sales must deduct that store’s stock. Otherwise the warehouse will keep sending goods a branch already sold.