Isabella Douglas

"Alexander of Dalhousie, who succeeded his grandfather before 19 March 1464-65, when Isabella, widow of George, fourth Earl of Angus, had a grant of his marriage for the purpose of marrying him to one of three of her daughters, whom failing, any of her other daughters. He had a confirmation of the grants of the lands of Dalwolsy and Foulden, in 1473, and another on 20 March 1473-74."

"He married Elizabeth Douglas, daughter of George, fourth Earl of Angus, and had issue"

from Scots Peerage (vol 3)

Note:

Elsewhere, in volume 1, Scots Peerage names this daughter as Isabella, and marries the third daughter, Elizabeth, to Robert Graham of Fintry

"Isabella, who, about 1464, was married to Sir Alexander Ramsay of Dalhousie, and had issue."

"Elizabeth, who, about 1476, was married to Robert Graham of Fintry, 2 and had issue. From her the present family of Fintry descend."

from Scots Peerage (vol 1) 1 2

References

1. https://www.patrickspeople.scot/ourfamily/6030.htm cites
   1. 1 e-books, The Scots Peerage ed. Sir James Balfour Paul vol. 3 (1906).
   2. 2 e-books, The Scots Peerage ed. Sir James Balfour Paul vol. 1 (1904).