I have added a option to choose quantity in frontend via backend custom options. It works properly, but the problem is that now there are two quantities on the product page, one is that I've added through backend and second is quantity for cart that is by default. These both quantities does not match, for eg. if I select 50, in the cart it only shows 1, which is by default in the cart. The price chanf=ges accordingly but the quantity in the cart doesn't changes. Please suggest me the way to fullfill my requirement.