I can't find a birth certificate/record for Melvin, but he was born 10 months after 17-year-old Della married George. But then 19-year-old Della married William Ratliff, and Melvin seems to have been given the Ratliff family name, which he used until maybe he was in his mid-late 20s (before WW1). The first record I can see of him as Turner is on his WW1 draft card. Do you know what happened to GW Turner? The Wikitree profile and related sources suggest that he died in 1909, so maybe he married Della, had a baby, then left? Did they divorce? Or...