Does anybody now of a product builder option for Zencart? (
(As in MYOB)

For eg: I have a product called "Harmony Ball" which is automatically deducted from stock when ever a purchase is made.

My difficulty is with a special of this product which is "3 x Harmony Balls"

It would be ideal if the stock would be deducted automatically from the stock of the first product. Otherwise I have to deduct 3 Harmony balls manually every time I sell a special.

I am not using attributes as I wanted a separate listing for the product to take advantage of the specials option.

Any ideas?