Jonathan is a real mystery - he just disappears. I can't find his death - and although his wife remarries, I suspect it may be bigamously. I believe Jonathan's parents were James Cheney, an ag lab, born 1801 in Earley, Berks, and Hannah born 1811 in Shinfield Berks. I believe Jonathan was one of seven children.: Sarah, Thomas, Lydia, Jonathan, Mary Ann, Emma and Emily. Do these names crop up at all in your family?
I haven't followed the siblings - though now you've reminded me of this branch I might give it a try. However, this is a few generations apart from your Jonas. What would help would be if we could find Jonas had a James amongst his descendants!