Re: Zachariah "Zack" Scribner line
Hope you are still following up on this two year old post. I have just connected to the Scribner line. It appears that my great great great grandfather was Curtis Scribner. I am guessing that he was the brother of Redin and Zachariah, all sons of William. I say this based mainly on the 1840 census (Missouri>Taney County>Benton Township p. 110b) which shows them all together on the same page.
Regarding your question, if you check out the 1860 census (Missouri>Taney County>Buchanan Township p. 937) it shows Zach with a 4 year old son named James, which seems to fit your dates.
Would be happy to learn what info and contacts you have gathered on this line, and to share whatever I come up with as well.