On 20 January 1802, Glengarry married Rebecca, the second daughter of
Sir William Forbes, 6th Baronet, of
Pitsligo. Their children were a son, Aeneas Ranaldson, born on 29 July 1808, and seven daughters, Elizabeth, Marcelly, Jemima Rebecca, Louisa Christian, Caroline Hester, Gulielmina Forbes, and Euphemia Margaret. Glengarry's estate was much mortgaged and encumbered. In 1840, after his only son and heir, Aeneas Ranaldson MacDonell, had come of age he sold the Glengarry part of the estate to
Lord Ward, later
Earl of Dudley, for £91,000. Some years later Aeneas sold the Knoydart estate to a Mr Baird. Aeneas died at Invergarry on 19 June 1852, leaving three sons, Alexander Ranaldson (1834–1862), Aeneas Robert (1835–1855) and Charles Ranaldson (1838–1868). Alexander emigrated to
Australia and died unmarried in
Dunedin,
New Zealand, in 1862. Aeneas drowned at the age of twenty and Charles died at sea in 1868 on his way home from New Zealand. Of their three sisters, only one, Helen Rebecca, married and had children, and by 1887 she was her father's sole heir. She married in 1865 Captain John Cuninghame of
Balgownie,
Fife, leaving descendants. Glengarry's sixth daughter, Gulielmina, married Hugh Horatio Brown, a
Midlothian advocate, and was the mother of the Venice historian
Horatio Brown. ==Notes==