According to the experience of searching Baidu, the original singers of Happy Birthday to You are patty smith Hill and Mildred J Hill. Lyrics: Patty Smith Hill, Mildred J Hill. Composers: patty smith Hill and Mildred J Hill.
The copyright of "Happy Birthday to You" belongs to Summy Company 1935 and will expire in 2030. This is the first copyrighted lyric. 1990, Summy was acquired by Warner Records for150,000 US dollars, of which the estimated value of Happy Birthday to You was 5 million US dollars.