Have you posted a message on the Orleans Parish board too?
I did notice on some census' the family is listed as Black and on one it said Mulatto.
People changed the spellings of their last names for various reasons...even siblings changed the spelling, so some brothers and sisters had different spellings.
A lot depended on the census takers too...some were horrible spellers and often, a long time ago, people were illiterate and really didn't know how to spell their names.
If you have time during your visit to New Orleans, try the main library or go to the website www.nutrias.org. It has a lot of information...look under Archives/Special Collections. Good luck!