Makeup and sub

Ability to have players who are registered for a full session to withdraw from one class date and make up in another class date. Ability to remove a player from one date of the full session. And then go to another full session class and add a make up for just one class date at $0. This would also be good to go to a full session class and a a sub for the "drop in fee" with out prorating the session. For example, for our leagues we charge $15 for a sub fee or $0 for a makeup, this is not the pre-rated fee for the class.