I think we are not talking about the same thing. I know how product complements work. What I need is for them to be variable, for example:
If I add ‘spicy oil’ to a pizza, $0.50 is added to the subtotal of the purchase. What I want is that the price of this spicy oil is variable: if the pizza is small its price will be 0,50€, if the pizza is medium the price of the ‘spicy oil’ will be 1$.
Do you understand what I mean?