Complex sentence: Wedderburn Castle, near Duns, Berwickshire, in the Scottish Borders, is the historic family seat of the Home of Wedderburn family, ancient cadets of the Earls of Home whose seat is The Hirsel, Coldstream.
Split into simpler sentences: Wedderburn Castle, Duns, Berwickshire, in the Scottish Borders, is a historic home of the Home family. The family were anciently cadets of the Earls of Home who live at The Hirsel, Coldstream.