I don't know if anyone ever answered you but here is what I know. The Wederstrandt Plantation in Plaquemines Parrish was called Harlem and is actually still standing despite Katrina.
Here are the co-ordinates of the plantation from Google Earth. 29 37' 28.61" N 89 54' 09.73" W You can see the house in the aerial shot.
The plantation was owned by John Charles Perry Wederstrandt, during the 1860's and I'm not certain whether other family members also owned it. J.C.P. never married, and lived a great deal of his time in New Orleans.
His father was Philemon Charles Wederstrandt, one of three brothers who came from Maryland and are descended from Conrad Theodore Wederstrandt.