Schools are a sort of outlier when it comes to copyright stuff in lots of ways. There are educational exemptions when it comes to showing a movie in class for example, and on stuff like this there are specific channels you go through to license the plays themselves, any changes you want or need to make to the scripts, the peripheral stuff like programs/posters/shirts, and even the songs that can ant cant be performed in the play. I believe it's little mermaid where one of the songs cant be used in the play for some reason. Sometimes the licensing folks can be giant PITAs to work with about cuts and changes as well (which my wife deals with a lot since she teaches middle school and has to edit out stuff that may be inappropriate for that age vs high school).
