I need to create a Shop listing for 1 item with different lot sizes and keep track of my inventory. For example, I'm selling THE SAME rubber band in lots of 10, 25, 100, 250 and I have a total of 1000 rubber bands. I want my inventory depleted by 25 when someone orders a 25-pack, by 100 when someone orders a 100-pack, and so on... I can't find a way to do that on Wix stores. The only way that I have found is to create an item variation by Quantity, but in this case, each variation requires a separate on-hand quantity, which isn't what I want... I want them all to draw out of the same pool of in-hand quantity... How can I properly achieve this?