Update: The Sister that Existed....But Didn't

My cousin Heather and my cousin Warren and I keep bouncing back and forth. Is the photograph Arlene and the missing sister Jean OR is it really my Aunt Flo and my Aunt Hattie? I can't believe that my Great Grandmother would have a photograph taken of just them when she also had Aunt Maddie. I keep dreaming of the girl with big brown eyes, I feel like she is trying to tell us who she is but with so little information and stories that were taken to their graves, how do we find her out? I have asked a friend in New York to do some research on the Photographer that took the photograph. If we can pinpoint when the Photographer was in business, we should be able to figure out if it's Arlene and Jean or Flo and Hattie.......OY!