Keep in mind that only the words to "Happy Birthday" are copyrighted.
The melody itself, to the best of my knowledge, is not protected by
copyright, since that melody is one composed in 1893 by sisters Patty
and Mildred J. Hill and published as "Good Morning To All."  It has
been public domain for decades.

It would take a bevy of high-priced lawyers to sort out the "Happy
Birthday" situation and only the Disney heavyweights are likely to be
ready to spend that kind of money to protect their "rights."

Matthew Caulfield
Irondequoit, NY