I found this interesting academic article that talks about the controversy about who played base on many motown songs. I came across it because I was listening to an Apple Music play list called Carol Kaye: On Session. There were a lot of motown songs, one in particular was Baby Love by the Supremes. Which seemed odd to me, because it seemed so in line with WDOLG.
I googled Carol Kaye/ Baby Love and found this article:
Reconstructing the History of Motown Session Musicians: The Carol Kaye/James Jamerson Controversy.
If we thought the background singers was a conundrum, so too are the session players. Especially since motown didn't identify who played on the records, and the producers would just put a song title down as a placecard, not that that would be the title, so musicians didn't known what song or hit they may have played on. Or as this article seems to indicate, the LA sessions might have played the song, but it might have been for a TV show, not for the actual record.

An interesting read.