Complex sentence: After the pair split up, Parfitt married Marietta Boeker, and they had a son, Richard (born 1974), and a daughter, Heidi Marie Elizabeth Parfitt, who drowned in the family pool at the age of 2.
Split into simpler sentences: After the pair split up, Parfitt married Marietta Boeker, and the pair had a son, Richard (born 1974). They had also a baby girl Heidi Marie Elizabeth Parfitt who drowned in the family pool at the age of 2.