Multiple Inventory location for production order

We manufacturers some products\ from outside with our raw materials. In this case I enter purchase invoice without qty and a production order with purchase qty.
We will keep some raw materials with our regular supplier and some raw materials will give to supplier at the time of order. In this case I cant track inventory usage of raw material keeping with supplier. Can you add separate inventory location selection for every line of raw material in production order.

This has been on the ideas list from the beginning: Production Orders - Enhancements. See item C.