Remember the controversey George Harrison got into with "My Sweet Lord"? The claim was that it was an infringement on another previous top 40 tune. Since changes to many tunes are similar, I believe it's up to the legal folks, who, sometimes are not trained in music, to decide copyright infringements. Some claims have been a little hard to proove.

I believe the copyright includes the lead line, words and changes.

Generally, ASCAP and BMI go after folks who profit from public performance of copywritten materials (Clubs, restaurants, office buildings, professional service locations, etc). Can't imagine that they would persue nursing homes, family picnics, charity events, etc.

That would really be cold, legal or not!

Russ