Complex sentence: Today the Duchesse de Mouchy, granddaughter of Clarence Dillon, is chairperson of the public limited company of Domaine Clarence Dillon, making Haut-Brion the only first-growth to be American-owned.
Split into simpler sentences: Today the Duchesse de Mouchy, granddaughter of Clarence Dillon, is chairperson of the public limited company of "Domaine Clarence Dillon". Today, Haut-Brion is the only first-growth to be American-owned.