Isabelle Mackenzie was the third daughter of Colin Mackenzie, 4th of Mountgerald and Emilia, daughter of Colonel James Fraser of Belladrum. She married Archibald Dick on 13 July 1825 at her father's estate (Mountgerald). Her oldest brother and heir, Colin Mackenzie, 5th of Mountgerald, followed his sisters to Jamaica, where he died at 35 on 1 December 1837. His younger brother Alexander inherited all titles but unfortunately died soon after. He was followed by the youngest son, Simon Fraser Mackenzie, seventh of Mountgerald, a Lieutenant-Colonel in the Madras Cavalry and father of Major Gordon's niece Mary Mackenzie.
Isabelle died in 1874 after losing her son Alexander in 1866 and was buried with him and her husband in Elgin Cemetery, Scotland. She chose the 91st Psalm for her tomb, especially the 14th verse.