The Boswell Sisters were were the most popular singing sisters of the 1930s.
Martha, Connee and Helvetia had a startling close harmony and interesting rhythmic way of singing that has captivated listeners for years and years.
Although i have not found any official information to confirm this, I have watched and listened to the sisters quite a bit and have come up with this conclusion.
In the video i have posted below and in the top right picture, Martha (the oldest) is sitting at the piano and singing lower harmonies.
Connee, (changed her name from Connie in the 40s and went on to have a solo career) is singing lead and sitting with Martha on the piano bench.
Helvetia is singing higher harmonies and is standing behind them.
It is to my knowledge that this is the parts they sang whenever they sang together.
Today i have one of my favorite Boswell Sisters songs, Crazy People, which always makes me smile and marvel at they way they can easily slide from one time to the next, slowing down and speeding up, it just sounds perfect.
Be sure to watch Martha, she appears to be having a wonderful time at that piano.
(please remember the music player at the bottom left of the page)