Lemuel GRAVES is seated est age is 16 putting the date of the photo at 1880.
The young girl to Lemuel's right is labeled Ethel Margaret Graves (who later on married Frank LEONARD). Ethel is Joseph's 2nd eldest daughter.
The Lady to Lemuel's left is inadvertently labeled as Mary Hart Graves (Lemuel future wife), however, it isn't her. We believe she is Ethel's mom Mary Chatham GRAVES, Joseph's 1st wife. Mary would have been 38 in 1880.