Complex sentence: He is the first female-line member of the Belgian Royal Family to be born a Prince of Belgium, with succession rights to the throne: his older brother and sister were created Prince and Princess of Belgium in December 1991, several years after their birth.
Split into simpler sentences: He is the first female-line member of the Belgian Royal Family to be born a Prince of Belgium, with succession rights to the throne. His older brother and sister were created Prince and Princess of Belgium in December 1991, several years after their birth.