Receiving Free issue material for an Order

Hi.

Using Production Orders with routing operations etc. 

A customer places an order and sends an amount of free issue material for the operations to be performed on.

So, Product A is made from material B (Which is free issued without the need for a purchase order).

Do I still add the Material to the Production BOM and set it to manual flush ?

Basically, the warehouse needs to expect to receive material as 'goods in' for the Production order without raising a PO.

I think this is fairly common in manufacturing.  What is the best way to do this in NAV 2013 ?

Thanks

Dave K.