Grease / West Side Story school musical performance rights

I have no idea if this post is going to be of any help, but what I was specifically wondering is if anyone here knew of details regarding the obtainment of performance rights for either "Grease" or "West Side Story"? I am attempting to organise a 2005 school musical for where I work, and this is the first time I have organised a school musical, so really have no idea where to start.

Any help that people could give me would be greatly appreciated. :)