Imagine I have receipts for Pizzas. And a template form where I can edit its ingredients. I add Basilikum to the receipts textarea: Tomatoes Mozzarella Basilikum and save it. The Basilikum is added to the Margharita item. Now I edit the form and its textarea again to Tomatoes Mozzarella The Controller saves these two items (and knows they already exist with the getIngredients('Margharita','Tomatoe') and the same check for Mozzarella) but how would he know that he should remove Basilikum? How do you code this in the most easy way?