Looks like Nancy Doolen Belew and Elizabeth Doolen Helm are different people; research continues. I have found much the same information as you and more. It seems confusion comes from accepting C.I. Doolen's 1933(undocumented) "The Doolen Family 1765-1933" without understanding its limitations. This publication can best be described as the descendents of their brother Daniel (1812-1877) and Elizabeth Mahon Doolen. It contains a rather curious, brief (1 p.) history of Daniel's parents and siblings; I reguard this part as a guide (where to look) only.