Mariée le 20 décembre 1656 (mercredi) avec James Graham, Marquess of Montrose 1633-1669 (Parents :James Graham, Marquess of Montrose 1612-1650 & Magdalen Carnegie ?1617-1645)dont
Burkes Peerage (1959) contradicts itself. Under Morton it says Isabel was the daughter of the 7th Earl. Under Roxburghe and Montrose it says daughter of the 8th.