Complex sentence: Ernesto Koplowitz had even married within the Spanish-Cuban Aristocracy to a woman bearing some Marchioness titles, but his two daughters, Esther Koplowitz, born 1950, and Alicia Koplowitz, born 1953, were still too young when he died.
Split into simpler sentences: Ernesto Koplowitz had even married within the Spanish-Cuban aristocracy to a woman bearing some Marchioness titles. Koplowitz' two daughters, Esther Koplowitz, born 1950, and Alicia Koplowitz, born 1953, were still young when he died.