We’re working with a client for whom certain Product Structures which contain a specified components specify a quantity of “As Needed” for it. This appears to be due to the fact that they always know they’re going to need this component but the quantity cannot be determined until the Manufacturing Process has actually started. Once this has happened the Manufacturing staff simply go and take what they need for the order that is in progress. 

However in other Product Structures this same component can appear with both a specified quantity and Unit Of Measure so there is no consistency

This particular component has no unit of measure defined for it (we can manage this using the * No Unit defined) UoM when creating the Part Master and when including it in a Product Structure it is added as 1*, but how can we manage this component both from a UoM (as it needs to have an * UoM in some cases and an oz UoM in others) and also an MRP perspective.