How can I find out if my mother African American maternal & paternal grand parent are related on both sides her grands mother maternal grand mother are Browns? My mother mother name is Clara Singletary, she married DK Moses, his mother name was Lizzie

It’s so complicated I will try and sum of the facts both my great great grand parents are African American, I found them on federal Census 1870 in Terrell county , Ga paternal  and the Maternal great great grand parents on 1880 federal census in Worth County , GA. However; it’s get complicated because both sides the names are so similar with the common denominator are Browns. Paternal grandfather Warren Brown born abt 1830-40, Wife Sarah Brown abt 1840 ( I do not know her maiden name)  now Maternal great great Grand Father is A.W. Brown Also called Andy  born abt 1830-35 born Soutg Carolina, his wife is Sarah Brown ( her maiden name is Hagen) she died in Detroit MI,  I both women had about 16 children. both maternal and paternal great grand mothers  are Lizzie Brown. Both lived in Worth County city Sumter for Lizzie Hagen brown and Ty Ty for Sarah Brown.  How can I find out if they are related. I’ve been searching and I’m am stuck, I stop for a few years and now I want to complete our family history. My mother and father are all gone, only my my half sister is left and she’s not well at this time. Any assistance is appreciated. Thanks again.