The Allen name was spelled both ways, Allen and Allin in the early census records as well, Preston was listed in the 1830 census as Allin. Some of the problem was that other people were putting it down, also, according to the 1850 census Lucy could not read or write. At that time Malinda was also illiterate. It is a mystery why they were dealing with Floyd County. Maybe Lucy lived at that time (1849) in Floyd County?
Tell me more about John's birth and death, I'm also interested in his wife and children. How did they end up in Oklahoma?