Do you know where John MANLEY was born in Co. Mayo? My Gr Grandmother, Ellen MANLY (the spelling is different but not uncommon in those days), was born in near Crossmolina, Co. Mayo 17 January 1839. That should be near to the birth date of John MANLEY.
Ellen was married to James CASEY of Co. Tipperary and had her first child, Richard CASEY, on 19 October 1857 in Columbia, SC.
Since the birth dates were in the same era I thought there might be a connection.