For what it's worth, I think there is a Joseph Davie in Louisiana, either 1840 or 1850 Census, New Orleans area. Is this one of your Davie loose ends?
My grandmother, born 1870s, had an uncle named Joseph Davie (b ca 1845-1850), who lived in Memphis, TN and married Elizabeth McClintic (sp).(1850 Census Madison Co, TN = PH DaviS)There is a family resemblance in the eyes to Governor WR Davie of NC fame, but we aren't from HIS line.Brother Joseph or some kind of cousin??