Complex sentence: Dian was the daughter of Jef and Karin Alberts; she had two brothers, John (also deceased) and Remco (Terhorst, Jef's firstborn son from a teenage-relationship).
Split into simpler sentences: Dian was the daughter of Jef and Karin Alberts. She had two brothers, John (also deceased) and Remco (Terhorst, Jef's firstborn son from a teenage-relationship).