I believe this is the connection that you are looking for.

Marie Onesia Jean-Louis, born Nov. 17, 1839 was the daughter of Don Louis Marie Jean-Louis, born Abt. 1810 and Élizabeth Célimène Simon Guillaume Declouet, born Abt. 1826.

Marie Onesia Jean-Louis married Jean St. Ville LeBlanc. They were married Sept. 24, 1862.

St. Jean's Cathedral Lafayette, La. Vol. #4 Page #212 #14. SWLR 7 Page #246. Witnesses to wedding were Jean Baptiste Narcisse, Alexandre Narcisse, and Don Louis Jean Louis.

Marie Onesia Jean-Louis was the niece of Jean Baptist Marie Jean-Louis Simon who married Marie Angelique Louis Sam.

1850 United States Federal Census

Name: A Luissem
Age: 28
Estimated birth year: abt 1822
Birth Place: Louisiana
Race: Mulatto
Gender: Female
Home in 1850(City,County,State): Western District, Lafayette, Louisiana
Household Members: Name Age
J Bte Jean Louis 35
A Luissem 28
Don Louis J Louis 30
C Simm 20
Louis Jean Louis 8
M Jean Louis 11
E Jean Louis 3

LaTour Genealogical Collection
http://www.latourgenealogicalcollection.org/