Her parents are "traditionally" seen as Colin Campbell, 1st Lord of Glenorchy and his 3rd wife, Margaret Stirling. However, the Red Book of Scotland shows this Mariota Campbell as daughter of the 3rd of Glenorchy.

Biography

Mariote Campbell Her parents were Colin Campbell, 3rd of Glenorchy and Mariote 'Marjory' Stewart.

Mariote married William Stewart of Balquidder and Baldoran before October 5, 1498.

Together they had the following children:

1. John Stewart, 1st of Glenbuckie;
2. Walter Stewart, 3rd of Baldorran;
3. Elen Stewart.

She died on August 12, 1537 in East Ayrshire, Scotland.

Family

https://rykbrown.net/TNG/getperson.php?personID=I18797&tree=BROWN

Duncan Stewart (1739) says:

"William Stewart of Baldorran, married Marion [sic: Mariot] Campbell, daughter to Sir Colin Campbell of Glenurquhy, as appears by a charter in their favours, granted by Robert Menzies of Comrie, of the lands of Emyr-Crechan [sic s/b Emyr-Crethane] and Croftyn-Terray, in the Earldom of Strathern and Shire of Perth, dated at Lochtay, the 5th of October 1498. This charter is confirmed by King James IV, the 25th of said month. By her, he had Walter and John, who is a witness to several charters , and designed Johannes filius Guliemi Stewart de Baldorran, particularly in 1508, granted by Glenurchy. Of him is Glenbucky. William of Baldorran is said to have had another son, Andrew, of whom Gartnafuaroe [sic - Andrew of Gartnafuaran was the brother of William, not his son.] Of these three brothers [sic] are most of the Stewarts of the South-west district of Perthshire descended, to the number at least 300 common people.

Addenda - For Emyr-Crechan, read Emyr-Crethane. These lands were talzied [illegible] of Walter, and his lawful heirs, to John Stewart, his brother. There is one Andrew Stewart, witness to this charter, who, perhaps, might have been Garnafuaroe's ancestor. The lands of Duchlass, in the lordship of Rosneth, and shire of Dumbarton, holden of the King in Feu, are confirmed to Walter Stewart, son of WIlliam Steart of Baldorran, and the lawful heirs-male of his body, which failing to William Stewart's lawful heirs whatsoevr, pub arch lib 13, num 370. By what evidences I have [illegible] of Baldorran, it appears that the traditional account mentioned in the note of page 133 [referring to the origin of the Stewarts of Gartnafuaran] is not well grounded."

Sir William married firstly by 1 May 1484, to Janet, daughter of Archibald de Buchannan,1st of Lettir, (she was widow of Robert Tosheoch, son of Andrew Tosheoch of Monzievaird, by whom she had no apparent issue), when they had a charter from her father for the lands of Lettir, in the Lordship of Strathgartney.

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https://en.wikipedia.org/wiki/William_Stewart_of_Baldorran

Sir William Stewart (c.1440–c.1500), 2nd Laird of Baldorran, 1st Royal Bailie of the Crown lands of Balquhidder, was a fifteenth-century Scottish landowner, and founder of the Balquhidder Stewart clan. He was the grandson of James Mhor Stewart who launched a failed bid for the Crown of Scotland in 1429.

Stewart married twice. His first wife was Janet Buchanan, daughter of Archibald Buchanan of Lettir (in Strathyre). They had two children:

1. Janet Stewart (born c1475).
2. Agnes Stewart (born c1477).

His second wife was Marion Helen Campbell, [SIC: MARIOTE] Of Glenorchy, daughter of Colin Campbell, 1st of Glenorchy, whom he married on 5 October 1498, and by whom he had three children:[3]

1. Walter Stewart, 3rd Laird of Baldorran, 2nd Bailie of Balquhidder, born c1480 in Baldorran, Campsie, Stirlingshire.
2. John Stewart, 1st Laird of Glenbuckie, born c1485 in Baldorran, Campsie, Stirlingshire.
3. Mariote Stewart, born c1490 in Baldorran, Campsie, Stirlingshire, Scotland.

In the portioning of Balquhidder which took place during the sixteenth century, the descendants of Sir William Stewart of Baldorran gained hereditary tacks of land.

Disputed Origins

https://www.wikitree.com/wiki/Campbell-2596

Marion was the daughter of Colin Campbell and Margaret Striveling.[1]

She married WIlliam Stewart before 5 Oct 1498.[1]

https://www.thepeerage.com/p1944.htm#i19436

Sir Colin Campbell, 1st of Glenorchy was the son of Sir Duncan Campbell, 1st Lord Campbell and Margaret Stewart.2 He married, firstly, Mariot Stewart, daughter of Sir William Stewart of Albany, before 1448.1 He married, secondly, Janet Stewart, daughter of John Stewart, 2nd Lord Lorn and unknown wife (?), circa 1448.1 He married, thirdly, Margaret Robertson, daughter of Robert Robertson of Struan, after 1448.1 He married, fourthly, Margaret Stirling, daughter of Lucas Stirling, before 27 October 1467.1 He died circa September 1475.1 He was also reported to have died on 24 September 1480.3 He was buried on 26 September 1475.1

Children of Sir Colin Campbell, 1st of Glenorchy and Margaret Stirling

1. Marion Campbell+4 d. bt 28 Apr 1530 - 23 Aug 1530. Married 1) Malise Graham, 1st Earl of Menteith 2) John Drummond
2. George Campbell1
3. Mariot Campbell1. Married William Stewart of Baldoran before 1498.
4. Helen Campbell+1. She married, firstly, unknown MacEane of Ardnamurchan.1 She married, secondly, unknown MacLaine of Lochbuie.1 She married, thirdly, Iain MacGregor, 7th Chief of Clan Gregor, son of Evan MacGregor, after first ravishing her.
5. John Campbell, 1st of Lawers+4 d. 9 Sep 1513

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The Descendants ofThe Duke of Albany From Duncan Stewart’s Genealogy
https://www.chuckspeed.com/balquhidder/history/dstewart.html

p.173 V. William Stewart of Baldorran. m. Marion, dau. of Sir Colin Campbell & Margaret, dau. of John, Last Lord Lorn. Living 25 Oct 1498.

• 1. Walter, his successor.
• 2. John of Glenbucky, of whom later. Living 1508.
• 3. Andrew of Gartnafuaroe, of whom later.

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"Wives and Daughters of John Stewart, 1st Earl of Atholl - Part 1" (Brad Verity et al, May 15, 2014). < soc.genealogy.medieval >

4) Mariote Stewart, married Colin Campbell, 3rd Laird of Glenorchy

She is called sixth daughter of 2nd wife by DP, 4th daughter of 2nd wife by BEP, and listed as the 10th daughter in SP Atholl (1904).

Most sources call this daughter 'Margery', but from her obit in the Chronicle of Fortingall, we know her name was 'Mariote', and that she died on 26 July 1529 [not 1524, as SP has it]:

"Obitus Mariote Stuart domine de Glenwrquhay xxvj die Julii apud Insulam de Lochtay, et sepulta in Finlark anno Domini mvxxviiij" https://archive.org/stream/blackbookoftaymo00inneuoft#page/120/mode...

Per Gordon MacGregor in the Campbell of Glenorchy pedigree in his Red Book of Scotland series, updated just this year, Mariote (whom he calls 'Margery') Stewart and the 3rd Laird of Glenorchy had an elder daughter,

"Mariota Campbell, m. by 5 October, 1498, William Stewart, 2nd of Balindoran, (he was widow of Janet, daughter of Archibald Buchannan of Lettir, by whom he had issue) and had issue": http://www.redbookofscotland.com/sample%20families/Campbell%20of%20...

If Mariote Stewart had a daughter who in turn was married by 1498, Mariote would have to have been a daughter of the 1st Earl of Atholl by his 1st wife Margaret Douglas.

References

1. Paul, James Balfour. "The Scots Peerage : founded on Wood's ed. of Sir Robert Douglas's Peerage of Scotland; containing an historical and genealogical account of the nobility of that kingdom", Edinburgh: David Douglas, 1905, Vol. II, Archive.org, p. 178 < Archive.Org > Sir Colin Campbell married thirdly, before 27 October 1467,' Margaret, daughter of Luke Stirling of Keir, and had issue : — 7. Mariot, married to William Stewart of Baldoran before 5 October 1498. p. 180 < Archive.Org > Sir Colin Campbell of Glenurchy, the eldest son, is said to have been "ane great justiciare all his tyme," and to have built the Chapel of Pinlarig." ... having married Marjory, daughter of John Stewart, Earl of Atholl.By her he had three sons, successively lairds of Glenurchy." [other sources show daughters as well.]
2. https://www.thepeerage.com/p15051.htm#i150505 cites
   1. [S37] BP2003 volume 1, page 493. See link for full details for this source. Hereinafter cited as. [S37]
3. https://rykbrown.net/TNG/getperson.php?personID=I2328&tree=BROWN Marion Helen Campbell, of Glenorchy Female Abt 1460 - UNKNOWN
4. "Red Book of Scotland, Volume 2" (Bot-Car). Pages 580-582. < Ancestry.com >; (document attached) Sir Colin Campbell, 3rd of Glenorchy, succeeded on his father's death at Flodden in September 1513 ... He m. Marjory, daughter of John Stewart, 1st Earl of Atholl, (she survived him and d. on the Isle of Toch Lay, on 26 July 1524), d. on 11 August 1523, and was the father of: 1. Sir Duncan Campbell, 4th of Glenorchy 2) Sir John Campbell, 5th of Glenorchy 3) Sir Colin Campbell, 6th of Glenorchy 4) Mariot Campbell, m. by 5 October 1498 to William Stewart, 2nd o Balidoran ... and had issue 5) Helen Campbell, m. John dubh MaGregor of Glenstrae (he d. in 1529). They had issue.
5. "Red Book of Scotland Volume 9" (Smi-You) Pages 216-218. < Ancestry.com >; (Document attached).
6. https://www.clanmacfarlanegenealogy.info/genealogy/TNGWebsite/getpe... shows her as daughter of the 1st of Glenorchy and the widow of Malise Graham, Earl of Strathearn, later 1st Earl of Menteith, b. 1407, d. Bef 14 May 1490 (Age 83 years) before marrying William Stewart, 2nd of Balindoran before 1497.