Thanks, yes, there is a field right now for "Preparation Notes" or "PrepNotes" in a recipe (as well as the shopping list).
Currently, items will combine only if they have exactly the same units, ingredient names and prepnotes. That is, it will add "2 tablespoons onions chopped" and "4 tablespoons onions chopped" but not "1 cup onion" and "2 tablespoons onion". We are working on improved unit/combine features in a future release... thanks!