The Mary you are asking about was a Kendall. She married Frederick Sessions 1818, and after he died, she married Isham J. Morris in 1829. Mary's sister, Elizabeth, married Charles Wesley Morris the same year. Isham and Charles were brothers.
I have your Isaac Morris (Jr., brother of Isham and Charles) and Mary in my database, but I didn't have her maiden name of Sharp. I don't have the initial B, though, for Isaac. Could you please send me the info on their children?