According to article 1 section 8 of the US copyright law which is governed by the Federal Copyright Act of 1976, it gives the right of preserving the natural objects of art and culture to the people who get the pieces registered with the copyright office.
Here in this case, the music pieces were not copyrighted in the first place. Those works were published though but just with the names of the artistic director and her professor. The bare sheet music which exists just has the name of the composer preceded by ‘By’. Through this gala event, the artistic director is also addressing her personal hatred against the affordable health care act launched by the Obama administration. She plans to use one of those songs of course with changed lyrics to condemn it.
According to section 8 of the US copyright act of 1976, the artistic director can surely go ahead and change the lyrics of the song as she desires.The song is not registered with the copyright office in the first place so it should not be an issue. Also if she wants to modify the lyrics she can but whenever the song is going to get registered, in good faith the professor’s name should also be present with the same. The credit should go to both the parties even though one of the parties is deceased.