He also contributed to establishing Belgium's diplomatic relations with the Grand Duchy of Tuscany, the Kingdom of Naples, the Papal States and the German Confederation.

In 1824, he was created Prince of Caraman in the Dutch nobility[1] In 1852, he acquired the Hôtel de la Pagerie at 17 quai Malaquais, in the 6th arrondissement of Paris, renaming it Hôtel de Chimay.

The widow of comte de Brigode, she was the daughter of Françoise-Marie LeRoy and Henri de Pellapra, a wealthy financier, although Émilie claimed to be a daughter of Napoleon.

[3][4] Together, Émilie and Joseph had four children: The Prince de Chamay died in London on 12 March 1886.

[19] Through his youngest son Prince Eugène, he was a grandfather of Countess Emilie de Caraman et Chimay (1871–1944), who married Hungarian diplomat Count Dionys Széchényi, and Countess Hélène de Caraman et Chimay (1864–1902), who married Anglo-Irish diplomat John Francis Charles, 7th Count de Salis-Soglio.