When running mrp processcing. If I have a subcontractor order of which requires a component to be delivered to the subcontractor and I create the delivery but dont validate it because lets say the carrier has not picked it up yet and I want to wait for that before validating the delivery. If I run mrp, it looses the item ans suggests I purchase or make another one unless I validate the delivery which takes care of the shortage. 

Does anyone know a way around this??? setting, parameter??

thanks