The background melodies of what? There weren't any vocals done for the piano bit, were there?
The piano bit is basically the H&V chorus in G#. The background melody I'm talking about is the:
"Bahm. Bahm. Bahm. Baa-Bahm. Baa-Bahm. Bahm."
Whether the vocals were recorded is an interesting point. I know Mike Love refused to sing "Sunny down snuff" for the Prelude. Still... that shouldn't've affected this. So if they had that session, then they probably did record the vocals for this.