Lady Mary Douglas Peerage person ID=152666 (1655–1694) Parents Lady Margaret Stewart James Douglas, 2nd Earl of Queensberry Children Alexander Stewart, 4th Earl of Galloway James Stewart, 5th Earl of Galloway Lady Henrietta Stewart John Stewart Lady Margaret Stewart Siblings Lady Margaret Douglas Lady Henrietta Douglas John Douglas Lady Margaret Douglas Lady Catherine Douglas William Douglas, 1st Duke of Queensberry James Douglas Lady Isabel Douglas Robert Douglas Partners Alexander Stewart, 3rd Earl of Galloway