Abraham had a son Samuel. That is known from the land partition. But when I couldn’t immediately find him in the 1850 Census, I was about to conclude he either died young or had become untraceable when I happened upon a find-a-grave memorial for him while looking for a different Samuel.

He is buried in Montgomery County, Indiana, the same place where his brother John had moved by 1840. Knowing that I did find him in 1850, his name mis-transcribed as Samuel March and then he was in Montgomery County thereafter.

Moreover, in January 1850, he was named the guardian for all of John’s minor children

He is designated P5b2.

Samuel Marts is indeed on find-a-grave. But when I first found him, his memorial only showed the dates 1821-1847, seemingly consistent with the fact that I was unable to find him in the 1850 Census, and I was about to close the book on him but I happened to notice there was an obituary there for him posted by someone else.

It said:

1.) He was born 19 Jun 1821 in Pickaway County,
2.) He married Mary A Baker in 1843,
3.) In Oct 1848, he came to Montgomery County
4.) He died there 3 Nov 1894

I still don’t know where he was in 1850, but knowing he lived until 1894, I then found hm listed as Samuel Marts in the 1860-1880 Census.