Have you tried multiply price in the pre mod section? You can limit mods to only add one mod, and create another mod group(like sandwich upgrades) to add anything else to the item.
Hi,When we were using default modifiers, we had a group of modifiers at no charge that came on an item and then created another mod group for example in your case you could call it Sandwich Upgrades. In the upgrades group you can add mods with price...
