I was so interested in this family line that I did some research.You may have these already:
"Land Records of the Attakapas District"by Glenn R. Conrad
Page 15628:136Procuration, 14December1813.Dr. Philip Zerban named Agricole Fuselier as his attorney in all matters having to do with the estate of the late Dr. Frederick Zerban, late of Texas, amounting to $2000.
Page 16928:257Procuration, 14April1814.Mrs. Fuselier Zerban gave power of attorney to (this is a partial - I got it from WorldCat on the web - only gives a snippet view, but you can find it in the book)
Page 203#2704Procuration 7June1815.Mrs. Fuselier Zerban gave power of attorney to Alexis Ferry of St. Martin Parish to represent her inthe receipt from Joseph Saul and Francois Bureau, syndics of the estate of Phillippe Zerban of New Orleans, all monies coming to... (only partial, ditto as page 169)