The Cart app will defend against a customer buying more than one set of instructions, since it is digital and is delivered on demand after the initial purchase.
[x] Can't add a quantity greater than 1.
[x] Removes Instructions if one of the other sets is ordered.
[x] Grays out add to cart button if any sku associated with item is in cart.
The Cart app will defend against a customer buying more than one set of instructions, since it is digital and is delivered on demand after the initial purchase.