Standing Room Only Theater Company

Hi All,Our middle school has been doing off named musicals for years and now we are trying to get them to do well known shows, like the Broadway Jr collestions. Our theater group, based in the same school district, has been doing Broadway jt shows for a few years and love them. The problem we have is the principal wants the orchestra kids involved, i.e. to play the show live, so we need the orchestra parts for them. Generally we have piano, drums, violins, violas, cellos, bass, horns etc. Our district has a wonderful music program so they really want everyone involved...Any suggestions?