 Isabella's second husband was Alexander Stewart, Earl of Mar, son of Alexander Stewart, Earl of Buchan, the feared "Wolf of Badenoch".Isabel Douglas, Countess of Mar died without issue and the claim to the Earldom of Mar passed to Robert Erskine, 1st Lord Erskine who was descended from Elyne, daughter of Gartnait (Gratney).Robert Erskine was recognized retrospectively as an Earl of Mar by an 1885 Act of Parliament.