Complex sentence: Her niece Mapita Cortés, Miss Puerto Rico 1957, joined them in Mexico City and briefly joined the Mexican film industry in the late 1950s, but she retired after her marriage to popular Chilean crooner Lucho Gatica.
Split into simpler sentences: Her niece Mapita Cortés, Miss Puerto Rico 1957, lived with them in Mexico City and briefly joined the Mexican film industry in the late 1950s. However, Mapita retired after her marriage to popular Chilean crooner Lucho Gatica.