As the backing duo for singer Tony Orlando, Dawn was among the biggest pop acts of the '70s. Vocalists Telma Hopkins and Joyce Vincent (later Joyce Vincent-Wilson) got together in Detroit during the late '60s and made a profitable living as session singers, most often for the Motown label (though Hopkins' highest-profile gig was delivering the line "shut your mouth" on Isaac Hayes' "Shaft"). There is some dispute as to how exactly Dawn hooked up with Orlando, or just how many of the group's early singles Hopkins and Vincent actually performed on. The first single credited to D...