Complex sentence: The song was "Why Do Fools Fall In Love" (which was originally reworked from a poem called "Why Do Birds Sing So Gay") and since Santiago was not present, Mr. Goldner asked Frankie if he could sing the song.
Split into simpler sentences: The song was "Why Do Fools Fall In Love" (which was originally reworked from a poem called "Why Do Birds Sing So Gay"). Since Santiago was not present, Mr. Goldner asked Frankie if he could sing the song.