Cherokee Tribe - Downing Family

Joel Mayes Downing was my grandmother's dad, her mom was Betsy Sunday. I don't know if that is supposed to be part of that info I can see. My Grandmother's name was Mabel Louise Downing, 7/8 cherokee, and she had many brothers and sisters, although I don't know any of their names. She married James Henry DeMoss, and that is where I am stuck. Rumor has it, that James Henry DeMoss had indian blood, but he never admitted to it. Much like admitting you're part black in the south in the first part of the 20th Century. Harold Gene DeMoss, my dad was their only child. My name is Deborah Ann DeMoss and can only prove 7/32nds of Indian blood because of James. Can you point me in the right direction? - Debbie