Product Item - Specify Multiple for marking as individually.

I would like to be able to specify a quantity multiple for when Americommerce ships individually. It's not always one! Let say we sell filters by the each and they are large. So, up to 12 can ship per case. We would like to be able to specify how many trigger a new shipment. Example: Customer orders 60, we mark as individually now it's 60 separate shipments. I'd like a block next to that so when we check the ship individually we can specify how many it takes for each shipment trigger. So like, mark the box then have a area for quantity we can enter like 12. The new trigger would be for each 12 a new shipment is triggered so that the UPS calculator works correctly.