It makes you crazy, doesn't it! Here is how I have it figured out. Christian Kellar marries Catherina Amsbaugh. A birth date of 1764 sounds about right for him. They have at least 3 sons that I can name, plus some daughters that I know only as hash marks on the census.
Son #1. George Kellar, b. 19 Jan 1796, d. 13 May 1871 in Cherryhill, Indiana, PA. Married Catherine Bower(s?) on 15 July 1823. The had the following children: Elizabeth, Peter, Mary, Nicholas, Hannah, and Henry. Also living with them in 1850 is a 3 year old William Davis, which may indicate an older daughter-or not, who knows.
Son #2- Christian Kellar, b.20 May 1803, d. 18 July 1876 in Buffington, Indiana, PA. Married Christina Wike (Wiek) on 16 May 1826. They had the following children: George J,Henry, Catherine, David, Christian, Mary, Margaret, Alexander, and Jacob.
Son #3. Valentine b. 19 Mar 1808, d. 10 Feb 1894, married Margaret Bower(s). Had the following children: Mary, Abednego (son, biblical name), Eve, Rachel, John, William Almira and Martha.

I also questioned Anna Maria Hart, I see two possibilities. Either my Catherina Amsbaugh died and her husband remarried as older man, or Son #2 was married to her and she died before or because of having a child and he remarried a couple years later.

It appears that many of the men named Christian in this family answered to "Christ",or "Christy". I think that "Christopher" comes about when someone else tries to turn a nickname into an official name. The only place I've seen it show up is on the census, so it may be an invention of a census taker trying to make things official.
I haven't found any of the earlier graves, who knows if the tombstones even exist or are readable now.
I would suggest posting your tombstone photos on findagrave.com It is a pretty cool site.

I just found the church book that I recommended to you this week, so I am still busy trying to add the documentation to my tree.
Raona