A flatted seventh interval is a second, JohnB--

For the life of me, I'll never figure out why you all are so dead set against studying a little music theory. It'd make life so much easier for you, because you'd know the words that describe what you are already doing--

Jerry is right of course--there are a lot of really different approaches that get bunched up under the "doo-wop" rubric(a name I hate, incidentally)--some lay the melody on top of a call and response between the bass and middle voices(who sing a rhythm pattern made of shoops and doops and boppas, usually on the third and fifth of the chord), some sing in unison and break into a chord at the end of the phrase, others sing the melody as block chords(almost like barbershop to a swing beat)--some have a falsetto soprano with the melody carried by the baritone, others have the soprano on top of the melody--

My thought is that you can double up on the melody notes(unison), and it is OK to have the melody note included in the "doo-wop" block chords--but it seems like it would create a serious balance problem if two voices were on the same note for any other part--