Your software is very flexible here but again I need specific changes. Product ingredients are shown and user can dis-select them but can not replace. I like to have to dropdown lists side by side from left user excludes the allowed number of ingredients and from right selects new ones free of charge. For example if I set user change one topping of pizza free of charge they do it here.
Response: Our system allows you to setup any number of product options combinations, and on this case select those ingredients , please check this video for example, I'm setting up a pizza that allows to select a min of 1 ingredient and a max of 3 at no extra cost, then it allows me to select other ingredients with extra cost. Please check https://www.dropbox.com/s/y4jng7bl5aw2qkc/2016-03-25_17-42-23.mp4?dl=0