James Erskine, 6th Earl of Buchan Scottish nobleman (1600–1640) Parents John Erskine, 18th Earl of Mar Marie Stewart, Countess of Mar Children Margaret Erskine Lady Mary Erskine Henry Erskine James Erskine, 7th Earl of Buchan Siblings John Erskine Lady Margaret Erskine Sir John Erskine of Otterstoun Sir Charles Erskine of Alva Lady Anne Erskine Lady Catherine Erskine Henry Erskine, Master of Cardross Lady Mary Erskine Partners Dorothy Knyvett Mary Douglas, Countess of Buchan