History of The Mackenzies by Alexander Mackenzie, 1879 - 1892
https://www.fulltextarchive.com/page/History-Of-The-Mackenzies1/
Sir Robert Gordon ('Earldom of Scotland,' p. 36) shows that the
Rosses were originally designated O'Beolan and Gillanders
indiscriminately, according to the writer's or speaker's fancy.
He says that -
"From the second son of the Earl of Ross the lairds of Balnagowan
are descended..."
........................
IV. HUGH O'BEOLAN, EARL OF ROSS. He received
charters, of Strathglass and of the Isle of Skye. He married first,
in 1308, Maud or Matilda, sister of King Robert the Bruce, with
issue -
1. William, his heir and successor.
2. Hugh Ross of Rarichies, from whom the Old Rosses of Balnagown,
of whom the last representative in the male line was the late
George Ross of Pitcalnie. This Hugh obtained the lands of Philorth
in Aberdeen-shire, and between 1362 and 1372 he exchanged them with
his brother, Earl Hugh, for the lands of North Argyle, including
the Castle of Ellandonnan. The territories exchanged included
Strathglass, Kintail, and other lands in Wester Ross.
3. Janet, who married, first, Monimusk of Monimusk and, secondly,
Sir Alexander Murray of Abercairny.
4. Euphemia or Eupham, who married, first, Randolph, Earl of Moray,
who was killed at the battle of Durham, and secondly, her cousin,
King Robert II., grandson of Robert the Bruce and first of the
Stuart dynasty. This marriage being within the prohibited degrees
of consanguinity a special dispensation was obtained from Pope
Innocent VI. for its celebration in 1355. She died in 1372.
Earl Hugh married, secondly, also by dispensation from the Pope,
in 1329, Margaret, daughter of Sir David de Graham.