Just my best guess that John Isam Davenport was their child - cannot find any relationship whatsoever to anyone else.
There is a matching Davenport in Russell Co, VA tho - "Kemper Davenport" also born Oct 1880 to Abel and Darthalia Davenport (1900 Census), but Abel, s/o Peter J and Catharine Davenport, are the other Davenports, and would not have named a son Isam (Isham). Elsewhere, says Kemper was born Oct 11, 1879, not the Oct 4, 1880 that John was. ( http://www.rootsweb.ancestry.com/~varussel/vitals/births/1879.html )
Inclusion of Morgan from maitai's "Our Family" tree on ancestry.com