Goods flow direction

We have one central distribution center(CDC) and dozens of regional warehouses(RW) all over the world. RW are located by region or country and they feed stores located in that region or country. To CDC, suppliers from all over the world send ready to use/wear goods. Goods arrived to CDC sent to RW according to the sales data of the region where RW is located. In RW goods are sent to regional stores according to the sales data. Stores can receive goods and send goods back to RW. But RW can not send goods to CDC because of transport and custom expenses it is not reasonable. Goods received back from stores can be stored in warehouse or sent to other stores in a short or long period of time.