Edit a custom meal (that's been added to the diary) without changing the original?
Shouldn't I be able to add food/custom meal, and then within that meal in the diary, be able to change quantities? It appears that the only option is to go to the original saved meal and change and save over the original version. Doing this elicits "Do you want to change/update all other meals already saved in the diary?" - and the answer to that is, of course no. Clicking 'no' then cancels the entire effort to change one ingredient in a meal in the current day's diary.
So how can I add a custom meal, then change the quantity for one ingredient, then save it to the current day without affecting all other instances where this meal is in the diary?