Desarrollar software

We are setting up an online store with prestashop that only delivers to 3 locations. We need to modify the order process in a way that the costumer will only need to fill the following : 1)full name 2)adress2 3)vat number Then the costumer selects the location from a drop down list, and based on what he chooses all the rest of the shipping information is automatically filled. Thanks in advance for your time.