Hi,
Ijust wanted to add on to what's already been stated.I am also looking at Carter G Woodson'Free Negro Owners of Slaves in the US in 1830. For Catahoula Parish there isnt any Francois Oliver or Elizabeth Oliver listed as Free Black slave owners for the year 1830,so that information may give you an estimated date as to when they became slave owners and/ or began to reside in Catahoula Parish as slave owners.

In St Marys Parish, I see a Romain Verdin listed as having 8 slaves,24 people in his household, and the ages were 36-55. Also In St Mary's Parish a Leon Verdin is listed as having 4 slaves, 15 people in his household ,and the ages were 24-36.

Ihope you find more information on the Verdins.