In George Washington Cable's literary work "The Grandissimes," what events led to the feud between the De Grapions and the Grandissimes?

The feud between the two families originated from a long-ago gambling conflict between Agricola Fusilier and Nancanou, husband to one Aurora De Grapion-Nancanou. Aurora, one of the female heroines of the story, was originally a De Grapion; when she married young Nancanou at sixteen, she became Aurora De Grapion-Nancanou. Aurora's husband was said to have been an educated man of "cultivated tastes."
Accordingly, on one of his business trips to New Orleans, Nancanou took to socializing with Agricola Fusilier, Honore Grandissime's uncle. Conveniently, Nancanou had dropped Aurora and their daughter off at her father's house before he engaged in revelries with Agricola. Both men eventually spent themselves into a stupor, alternately drinking, dancing, and gambling together. On one of those dissolute days, Nancanou found himself on the losing side during a gambling bout; down to his last quarti, he realized that he needed to adopt some desperate measures in order to recoup his costs and to protect his reputation.
So, Nancanou pledged the whole of his estate against a play. It was said that Agricola initially refused to take up Nancanou on his offer, but he soon relented. In the end, Nancanou lost badly and accused Agricola of having cheated his way through. Incensed at having his integrity called into question, Agricola challenged Nancanou to a duel. Before the duel, Nancanou sent Agricola a clear title to his estate, lacking only his wife's signature to legitimize the transaction.
The duel ended with Nancanou's death. In the aftermath, Agricola wrote to Aurora with a stipulation: Aurora could keep her husband's estate if she would agree in writing that "the stakes had been won fairly." If she refused, Agricola would claim the land and holdings for his own.
Gravely insulted by Agricola's terms, the widowed Aurora and her father both wrote back a coldly polite letter, inviting Agricola to lay claim on the land if he so pleased.

They kept all their rage to themselves, and sent the polite word, that they were not acquainted with the merits of the case, that they were not disposed to make the long and arduous trip to the city and back, and that if M. Fusilier de Grandissime thought he could find any pleasure or profit in owning the place, he was welcome; that the widow of his late friend was not disposed to live on it, but would remain with her father at the paternal home at Cannes Brulées.

Eventually, de Grapion (Aurora's father) passed away, and since his property was greatly mired in debt, both Aurora and her daughter, Clotilde, became homeless. They soon found themselves in New Orleans and according to Dr. Keene, "without a male protector" and ostensibly "without adequate support." Because of these events, the legendary feud between the de Grapions and Grandissimes soon came to be known throughout New Orleans society.