Yes, it's pretty established many of the Jackson 5's recordings used background singers other than the brothers [[and with the brothers). Let's take the early recordings [[1st 3 albums), for example. Did any of these most likely use only the brothers' backing vocals? A lot of the slower, ballad-like numbers [[i.e. "I'll Be There") used very intricate harmonizations which, in my opinion, lead me to believe that these are mostly [[if not all) session singers. Thoughts?
I've never heard of them using session singers, but I did hear that songs like mama's pearl, it was just Michael, Jermaine and Jackie.
From what I read, most of the Jackson 5's recordings that became hits, only Michael, Jermaine and Jackie did vocals to. I don't think Tito and Marlon were much involved in it unless they were called to add ad-libs [[as Tito did in some songs, like ABC and Marlon in I'll Bet Ya). Tito & Marlon weren't really that active in background vocals for J5 work until probably '72 or '73 [[especially in '73).
BT told me only the brothers sang on their records.
All the Jackson 5 original multitrack sessions I've heard sound like the brothers and you can even hear them in some cases talking and joking before the tracks start. Even on Michael's early solo work.
I've never heard this even proposed. When I listen to these albums, as a guy who loves listening for and identifying individual voices, all the brothers sang on those songs. Marlon's voice could have been brought to the front more, but like Otis Williams, his voice is the glue to their harmonies. Tito's bass is there. Basses don't seem to get a lot of play or respect in popular music. Their vocals are brought up front when needed, but they anchor those harmonies. Sometimes you may not be able to hear Melvin, but he's there... same for Obie, Pete Moore, and Tito.