Complex sentence: Nick and Evelyn later divorced in 1990, and both remarried; when she was 13 years old, Welch, her mother, and her two younger siblings moved in with their next-door neighbour and his three teenage children.
Split into simpler sentences: Nick and Evelyn later divorced in 1990, and both remarried. When she was 13 years old, Welch, her mother, and her two younger siblings moved in with their next-door neighbour and his three teenage children.