Eleanor Tolliver Waters info in Edgar Cress’ book does show 2 daughters both named Mary. (SV-404 pg 709)
1850 Letcher Co., KY census: Aged 26 living with parents and 7 siblings. (SV-1069) Could she be a grand daughter??
1860 Letcher Co., KY census: Aged 78 living with Mary (28); Esther (24); May (20); Mary (15); James (11); Sarah (32); Manerva (8); Henry (6); Joseph (4); Jane (2). (SV-1071)