Create form based on birthday field entered?

I'm using HikaShop and I'm trying to create a form but I have question about how to create Based on the birthdate = a group of products in Hikashop – This is a checkbox and when clicked, the total amount of the invoice adjusts itself automatically. It
also has to be quantity related to ensure enough availability for that group of age.If quantity is 0, the product should not appear. Is this possible? Please give me quick response...
Best regards,

Hi,

One solution would be to create one option product with all the birthdates possible. That way you would have one variant per birthdate with it's own stock and you could add that option to a product and have it displayed on that product's page.
Is that what you want ?