* Kate Nilsson: While there is no publicly available information about Kate being a professional musician, she is a writer and has been involved in the music industry in some capacity. She co-wrote the book "The Ballad of Harry Nilsson" with her father and co-produced the 2015 documentary "Who Is Harry Nilsson (And Why Is Everyone Talking About Him)?".
* Joseph Nilsson: Joseph is also not a known professional musician.
Therefore, there is no public information about Harry Nilsson's children being professional musicians.