Hidden Classes - where we can enrol students in a class that does not show up in their portal

Would be nice if I could enrol students into a class for "back end use" without having it show up in their portal. For example, I would like to place my award winners into classes for the recital so we can use it in the recital wizard for teachers to gather them during the event. But I do not want the dancers to know ahead of time that they will be winning an award.