After 4 versions ps has still missed the point on inventory control. But don't bother I know the answer "that feature isn't supported in ps." How does this work. I have a pile of shirts in three colors to sell. So according to ps that's one product with options for color. Great! One SKU, one inventory quantity for all the shirts. So I sell a shirt, and another, and another. The quantity gets decremented. But wait, I sold out all the blue shirts and only have white and red left. Next five buyers all want blue shirts and buy them. Now I have to email them and tell them the blue shirt isn't available because...because...I'm out of excuses. I just break down and tell them that I relied on this product called power store that is...well...just wimpy store.
For inventory control on any website the SKU, weight AND the quantity belongs on the variation not the product. Every single variation needs its own row in the table. Which isn't the product table but the inventory table.
I'm now evaluating if I can get enough other benefit to justify the cost including the effort to fix what wrong with ps. Next release I'd really like a little more thought but into this major issue.