I see two Jeptha Knights in Alachua County: one born between 1815 and 1820 in Georgia, who married Mary Mariah Watsonhttp://www.alachuaclerk.org/archive/AncientJ/FrontPage.cfm?B...
and one born in Dec 1886 in Florida, the son of Lemuel and Ada.
The will of George Knight (http://www.alachuaclerk.org/archive/AncientJ/FrontPage.cfm?D...
) leaves much of his estate to his nephew Jeptha for the use and benefit of Jeptha's six children: David Levy Knight, George Montgomery Knight, Thomas Jasper Knight, Margaret Frances Knight, Julia Eliza Knight, and Lemuel Lafayette Knight.
This is apparently the George Knight born in 1800 in Georgia who in the 1850 census was living in Alachua County with Jeptha Knight born in 1819 in Georgia, his wife Eliza, and four of the six children named in the will.
I see that Britton died in Alachua County in 1842, and his will isn't available online but can be requested from the clerk's office for $1 per page. Someone local can go in and take pictures (or use a handheld scanner, as I do).
I hope that helps. If you can provide any additional information, I might be able to find more.