Hi Neil, in case you haven’t found a solution yet, you can create case packs (or make sure that customers order in specific increments using our app Simple Bundles. First, you create product variants (e.g. 12pack, 24pack, 36pack) and bundle the individual products in those increments so that your retailers can choose from a dropdown with those variant options. When they add the product variant (e.g. 12pack) to cart, they’ll just see that variant and you’ll see on your Admin > Orders that the retailer has purchased 12x the individual product and also decrement the inventory. Hope that’s helpful! Please feel free to reach out to me if you have any questions.
Here are some examples: