Complex sentence: John Wedderburn Halkett was born in Dunfermline, Scotland, an HBC director, his second wife, was Lady Katherine Douglas, sister of Thomas Douglas, Earl of Selkirk.
Split into simpler sentences: John Wedderburn Halkett was born in Dunfermline, Scotland, an HBC director. His second wife, was Lady Katherine Douglas, sister of Thomas Douglas, Earl of Selkirk.