dealing with Customer owned RM

Hi all! This is my scenario: 1.Customer service receives order from customer 2. A sales order must be created for the Item A 3. the company need to purchase item B ( which is the same as item A) 4. the vendor is invoiced 5. we reduce stock for item B for the same qty (neg adj) 6. We improve stock for item A for the same qty ( pos adj) 7. Customer service is advised now that they can issue an invoice . This will relieve the inventory of item A. 8. When the production is made for item A , the final product will be item C because labor + another bom item E are added. So item C has a production Bom attached 9. When we receive customer orders, a sales order is entered. Upon shipping and invoicing, the inventory is relieved in consequence. Soma advices on how to handle this case??? Thanks RF