I can send you my info on Josiah but I am up to five pages I think.There is no direct link to Jehu Bostain.Josiah is the son of Jacob(1785) who married Salome Stirewalt.Jacob was the son of Andrew Bostian and Dorothy Cope. Jacob and Andrew were from Rowan co, I think and Josiah was from Iredell.
Josiah was the only member of his family to locate to TN. I am now aware of any of his siblings or cousins removing to TN altho I would guess there must be some relatives somewhere in TN.There certainly werent any in his part of TN (Perry and Hickman co).
Occasionally Josiah's name was spelled Bostain but usually Bostian or just Boston.I think his cemetery stone might say Bostain but I have not seen it so I am not sure if that is true or a transcription variation.