Sales order cancelled and new sales order with added components

Hi all,

There is a MTO scenario.Lets say a product X was to be made .Now when the production was complete,the sales order got cancelled and a new sales order was generated for same product with 2 new components to be added,lets say A and B.

So now i have to use the finished good x and new components A and B for the new sales order.How will the costing of new product be done and how do i maintain the BOM?