I think that could be difficult. However I got some names of musicians which were part of the orchestra:
Marty Harrell - played trombone (subject to correction) also sat instead of Joe Guercio as leader of the orchestra during the March tour 1977 and a number of shows from May til June 1977
Tony (surname unknown) - played guitar at least in Vegas December 1975
Jimmy Mulidore played the flute solo for 'American Trilogy'
Those are the ones I know of.
Maybe others know names of other musicians.