Twin of Francis Marion Harwell

I live in Grants Pass, Oregon with my Husband, A. J. Harwell and Blue Heeler, Cheyenne. We have a "Brick Wall" beyond my Husbands Grandfather Francis Marion Harwell, G.Grandfather James Monroe Cox, John Samuel Reid and Jacob Pearson. DNA Tests show that my Husband has an exact mathch with Families with the spelling of Harell. Daughters of Francis (Frank) Marion Harwell say he had a Twin Sister nemed Gertrude and one Daughter had a Picture that I have posted on Anciaent Faces. Census records show Francis was born in Texas and his Father in Mississipi. Any Help or Suggestions will be appreciated.