Alvin Delos Allen (1806-?) had my relation, Delos Allen (1853-1905). Delos Allen had 2 sons: Harry D. Allen (1875-1954) and Delos V. Allen. I do not have any info on Delos V. Allen but Harry D. Allen had 3 children, one of which was a son: Marion W. Allen (born in 1903).I will see if any of my family has kept in contact with the Allens from this line.
If you come across any additional info on the parents of Seymour Allen, please let me know.