McQuire introduced a group of four singers to Lou Adler, his producer, who signed them. The group became “The Mamas & Papas”.
Before recording their first album, the M&Ps sang backup for McQuire to earn a few bucks.
Here’s a video of McQuire singing “Do You Believe In Magic” with Michelle, Cass, Denny & John singing background.
https://www.youtube.com/watch?v=53aTJHV2B3w
Maguire also introduced the gospel group “The 2nd Chapter of Acts” I believe. Or was an early supporter of them