The CASK Registration form is the same one used back when the Community Starter Kit was written in .NET 1.1; a wee bit outdated and not up with the times, i.e, won't have MySpace, Facebook or Twitter entries.

If you attempted to remove or modify the existing controls you would be greeted with something like the following error:

With the recent changes made you can now delete un-used textbox controls; they are no longer tightly coupled to the baseclass code.   Each textbox in the default registration screen is also tightly coupled to a database entry.   My recommendation is to reuse existing database fields and simply change what is shown to the user, i.e., I use the Occupation and Location fields for "Student Name" and "Relation" fields.

Important note:  Do not change the Master user controls in the Communities\Common\Themes\Default folder.  Instead copy and paste the controls you want to override (replace) in the applicable Theme folder.  By default you do not have to have any controls in your theme, it will use the defaults.  In the case above I modified numerous controls to include the user registration and profile controls.