Write some Software

We have a book e-shop on joomla 2.5.28 with virtuemart 2.6.18. We want to setup specific registration pages (with custom urls) that automatically add the user to a specific group. Specifically, my client has schools that each have their own prices and reading lists, so we setup the school with a custom home page (per joomla user group) and they also have a custom price rule (per vm shopper group). What we want is for the students to register automatically on their user and shopper group so after registration they can use the store immediately. We do not want a drop down on the registration page, we want specific registration pages that automatically add the user to the specific user and shopper group. We also want all code passed on with overrides so that virtuemart can be updated in the future.