Additives are a very useful function for species differences may have on sale. For example, when we order a souvlaki without saying tzatziki or without tomato. So we step in selling souvlaki with pita bread and then choose the product without tomato and tzatziki free product.
To use this function needs to settings–> units to build a new unit of measurement eg Additional code 1000 and after the warehouse to define the types you want the same unit.