If you want to be able to place a PO for those rare inventory items, or want to be able to use the resource allocation to tell you want's needed for the order then you will have to put these items in the system just like your other inventory. I'm thinking one way to help you with this would be to create a trigger/triggers that will alert you when a certain product/attribute is ordered that will require those things youdon't have on hand, then you'll immediately know to order them...
