Have you checked Find a Grave? There's a Geneva Crawford Bellamy b 1924 d 1988 (as per your Geneva) in Horry County, South Carolina. Is this "your" Geneva?
You mentioned that "your" Geneva had a sibling Evelyn, which fits with the daughter of Uncle Eddie (who would not be a sister but might be "like" a sister, as the two lived together and were the same age).
Here's a Geneva Martin born 1924 in South Carolina. This Geneva is the same age, same name, same town as the other Geneva Martin (the one living with her uncle Eddie).
1940 Galivants Ferry, Horry, South Carolina Boyd Martin 43 born about 1897 in SC Dorothy Martin 21 WIFE, born about 1919 in SC JD Martin 17 Jeneva Martin 16 <----------------------- Vernon Martin 4 Marline Martin 2 Presley Martin 11 months
More about the Geneva Martin found with father Boyd Martin:
Boyd Martin was born 1898, died 1958, buried Rehobeth Methodist Church Cemetery, Galivants Ferry, Horry, SC
Boyd Martin’s wife is Bulah in the 1930 census when daughter Geneva is age 6. She is Bulah Williamson Martin born 05 April 1894, died 12 October 1934, buried Rehobeth Methodist Church Cemetery, Galivants Ferry, Horry, SC
Boyd Martin’s wife in the 1940 is called Dorothy; she is Dorothy Byrd (per Find a Grave obit for Joanne) and Boyd is called Harvey Boyd Martin.