According to my information Oliver Jacob Davis did not have a son named Francis Marion (Frank) Davis. My research shows a Frank I. Davis as the eldest son of son of Oliver Jacob Davis and Lavina Mildred Bullard. He was born 1877 and died between 1910 and 1920 (wife is listed as a widow in the 1920 census)
I believe the Francis Marion Davis you have listed as son of Oliver Jacob Davis is actually the son of Thomas H. Benton Davis and Parthena Chitwood. He was born 30 April 1881 in Drumwright, Oklahoma and died 1951 and is buried Sunny Lane Cemetery in Del City, Oklahoma. Information from a U S Social Security Application and Claims Index 1936 - 2007 states: male – Thomas H. Benton Davis, spouse Parthena Chitwood, child Francis Marion Davis. I have more info if you are interested.
I did not find any connection between the Oliver Jacob Davis family and Thomas H. Benton Davis.
Sincerely,
V