[4] Another brother, Sidney played violin in the Indianapolis Symphony Orchestra from 1945 to 1978 [5] The family had one sister, Fannie (23 July 1919 – 8 January 2010) who was an associate law librarian at the University of Southern California.
[6] Szathmary began arranging for a variety of orchestras, including Benny Goodman in 1934, Emery Deutsch in 1935, Artie Shaw in 1936, and Andre Kostelanetz from 1936 to 1977 and from 1937, Paul Whiteman[7] until joining Jack Teagarden in 1940.
During World War II he transcribed many orchestral pieces on V-Disc for American servicemen and began recording arrangements for featured singers such as Frank Sinatra and Mary Martin.
He composed the music for a 1950 United Nations radio program about drug addiction called The Shooting Gallery that was narrated by Gary Cooper.
When his comedian brother Bill arrived in New York in the early 1950s, performing stand-up under his birth name Szathmary, Irving admonished him with "Don't you know that I have a reputation in music?"