we sell parts over the counter or in conjunction with other parts. you guys use food as most examples. so i will try that. if a customer comes in and buys a pizza, the modifier could be pepperoni. but that pepperoni doesn't come out of my inventory, nor do i know the "cost" of the pepperoni or how many i have. but i also sell pepperoni over the counter for the same price which IS in my inventory with "cost" associated with it. i use modifiers as so my counter help knows what goes along with what. but it screws up my inventory and costs