Fixed Quantity Required on Shop Order Regardless of Shop Order Quantity

We have a need to add a fixed amount of resin to our manufacturing order
(for purging).
For example, regardless of the shop order quantity, we would add another
100 pounds
to the order.

I could manipulate the shop order quantity in MODATA. But we would like to
do this via
the BOM so it gets included in the standard cost of the product not as a
variance.
And we would not want the yield factors to impact this quantity.

Does anyone else do this and how do you accomplish it?

Thanks and have a good weekend!
Bonnie Lokenvitz
Engineered Polymers