Ability to update inventory based on portion sizes?

[DaveRyanMedia]

Hi,

I have a client that is a restaurant, they have a take out service and some of their menu items are based on portions. The issue they have is they have to pre-define the amount of stock per portion, where they would like to have it dynamic. 

example: Meal A has 3 portion sizes Single(100g), Double(200g), Party(400g). If the total stock they have of this item is 1400g is it possible to only show the Party(400g) to be out of stock only when the combined sales of the product is below 400g? and the same with the other sizes?

I have been looking for an app that can do this, but the customer isn't just using weights, they also use portion and volume sizes. Any advice or app that could help with splitting a single product based on its components would be a blessing.

Thanks