One “Add to cart” button per category

Hi gurus,

I’m devoloping a webpage for e-commerce with Categories, Sub-Categories and Products.
In each Sub-Categories the customer can only buy the exact quantity of the Sub-Category. So, for example, if the Sub-Category is “5 meals” the customer can only select the exact number of 5.

What I’m trying to do is:

– Remove the “Add to Cart” button from each product. The customer can only select the quantities for each product.
– In the Sub-Category page, only one “Add to Cart” button should be visible.
– If the customer select less or more of the Sub-Category quantities, then the “Add to Cart” button should be grey.

Example 1:

Sub-Category: 5 meals
14 different meals to choose
The customer select 2 quantities of meal.1, and 2 quantities of meal.2

Expected results:
– Add to cart button grey
– Legend: “You have selected 4 meals, and you have to select 5”

Example 2:
Sub-Category: 5 meals
14 different meals to choose
The customer select 2 quantities of meal.1, 2 quantities of meal.2 and 1 quantity of meal.3

Expected results:
– Add to cart button available
– When the “Add to cart” button is clicked, the customer will see the 5 meals selected in the cart.

I hope you can help me.
Thank you in advance.

The page I need help with: [log in to see the link]