say I have 100 widgets that I want to sell in packs of 1, 5 or 10. the only way I can work it is to set each to, say, 5 (50 + 25 + 5) and update each manually, or set them higher and run the risk of running out. whereas what id like is just set the stock to 100, and then each sale can lower the stock level by the required amount so im not in a situation of having run out of single items but still have 10 packs in stock..
