It was copyrighted by Jessica Hill, sister of the songwriters, Patty and Mildred Hill. She enlisted a music publisher to help.
The actual authors never saw a penny for their song.
Half right. Mildred Hill died in 1916, and never received any royalties. Patty Hill did receive royalties, and since her death in 1946, the sisters' share -- about $1 million a year, according to the publisher a few years ago -- goes to the Hill Foundation.
As I recall, there wasn’t a problem with Happy Birthday until “Sir” Paul got a hold of the rights. The Marcarena guys did this with the Girl Scouts as well.