Group part numbers for supplier price break?

One of our suppliers makes custom fittings for us, for which we have a couple dozen part numbers. However, there are only 4 or 5 basic molds, each of which can take a number of other options. Is there a way we can "group" the part numbers together so that Supplier Price List can add all the quantites together to get the price break?

Ernie Lowell
Diba Industries