Complex sentence: He bought the Paris residence from Boni de Castellane in 1914 Emilio's sister, Natalia Terry y Sanchez, had married Stanislas de Castellane (1876-1959), younger brother of "Boni" (1867-1932), the famous dandy.
Split into simpler sentences: He bought the Paris residence from Boni de Castellane in 1914. M. Terry, brother of my sister in law Stanislas His sister, Natalia Terry y Sanchez had married Stanislas de Castellane (1876-1959), younger brother of "Boni" (1867-1932), the famous dandy.