Allow user to choose

Here is the background of my issue, I have four registration forms that each are for a different role. Originally it was three now we are creating a new catalog for high schools, each high school has a specific role and catalog. The perfect way of getting this done would be to have on the built in drupal form the ability for the person registering to choose multiple high schools if so desired. The problem I am running into is when I enable the allow user to choose it shows on all the registration form, the ones I built in content profile and the built in one. Is there a way to make this so it only shows on the default registration form.