I've been at the brick wall on G-Grandma Atterberry. G-Grandpa Wm. R. Johnston is, himself, the grandson of Robt. Johnston, as you reported, and Sarah Snidow. The Sarah seems to be a family name as Sarah Snidow's mother was Sarah Pickleheimer.
For your own info...Wm. R. is buried in Marionville, Mo. The family story is that Sarah Ann left him when he became abusive after the kids were grown, and that she went to live with a sister in Colorado, maybe Greeley, where she became ill and died.
Do you know how the name SNIDOW is pronounced? Sny or Snee? Dow to rhyme with 'how' or 'doe'? LOL, I've never come across the name.
I'm delighted to get your information. Now I have a lead to search census records with. William the immigrant is especially helpful, thanks again...if you're continuing this line, my page at http://thurmania.com/Thurman2.htmlhttp://thurmania.com/Thurman2.htmlhas Olive's family.