Hello Kat, I've just now read your posting and I believe that you may be talking about the same family as my husbands family.
I have the line like this:
John T. McKown b 1770 m. Nancy Griffith 21 Dec. 1802 They had following children: John McKown m. Polly Jones and had son John T. McKown then John married a second time to Grace Jones in 1818. Betsy McKown b1803 and m. Thomas Spady on 8 May 1821. William McKown b24 Sep 1803 d. 23 May 1856 m. Eizabeth Ann Nottinghgam b20 May 1807 Caty McKown b1812 m. Walter Stringer m.28 Dec. 1830 Frances McKown b1817 m. Custis F. Williams m. 1835.
My husband's line comes from William who married Ann Nottingham. Their daughter Ann "Nan" Nottingham McKown married John Frederick Williams and he is my husband's grandfather. "Nan" was born in Capeville VA. We have two different dates for her birth, so I'm not sure which is correct. One is 1875 and 1884.
I'm not sure which William is yours...but I believe it might be the son of the William I've listed above. This William had the following children: George W b1831., William b1833 who we have as married to Sallie Griffith on 17 Jan 1855 (he could have married twice and hence be your William), Lucie Ann b1835 who married Washington Hunt in 1855, Arenthia b1839, Ino b1840, Chesleton Kenneth McKown b1842 m. Susan Roberts, Missouri b. 1847 and Fanny b1850.
However, the dates may not be correct here for this line to be directly related, but the names are too similar and location of Northampton to not consider it a possible "same family" match.
Perhaps your research has gotten you beyond the point when you posted this message and you might be able to connect the dots. Let me know? THANKS.