Can I add songs to a Jr. version?

Our students perform Jr. versions of shows at the elementary level. I don't think our middle school is quite prepared for a two hour show, but I would like to add a few more songs for them so they are performing a bit more advanced version than our elementary schools. We were looking at the Music Man and wanted to add Marian the Librarian and Will I Ever Tell You. Is this something I can request to add to the Jr. version through MTI?