Hi, this is what im trying to do:

I made an inventory management, that was easy, I just did the content type product with its respective fields of cuantity, and others.
In a view I did 2 tables the normal stock and the critic stock, where I show the name of the product, the quantity and 2 buttons for each product, the button (+) and the button (-) those buttons are for add or remove products of the stock, you understand, this is an example