Complex sentence: He had one Sister Miriam Kathleen (Strachan) Dunbar who remained in Petersham New South Wales Australia-Miriam Married William Thomas Strachan, the Children of that Marriage being Miriam Kathleen, and William James Strachan.
Split into simpler sentences: He had one sister, Miriam Kathleen (Strachan) Dunbar who remained in Petersham, New South Wales, Australia. Miriam married William Thomas Strachan, the children of that marriage being Miriam Kathleen and William James Strachan.