Raw material and Finish Product from Diff Supplier - Unit cost

Hi ,

We are using NAV 2016 and our costing method is weighted average cost.

I would like to have a solution for below scenario.

Item-A - Raw material - from Overseas Supplier 


Item - B  - Finished Product  -Local Supplier 

Item - C - Finished Product   - Local Supplier 


Importing raw material ( Item- A ) from an Overseas supplier and we pass that Item to the local supplier to make the final products (Item -B & Item -c). 

Item-A received through purchase order and posted with proper actual landed cost.

We are receiving local supplier invoice to produce the item-B & Item-C from Raw material Item-A.

Currently, we are practicing  Negative adjust to raw material item code and positive adjustment to finish products code with unit cost ( Raw material cost + Value added cost ).

what is the correct way to post the Finish products & Raw material consumption and update the vendor account for above scenario?