What sources prove these as children of Madach, 1st Earl of Atholl
Myrun Maddaðardóttur Bjadmakdotter
Margaret de Caithness ?
Hang on: Found one
"31. kafli Auðun átti Mýrúnu, dóttur Maddaðar Írakonungs." Landnámabók
https://www.snerpa.is/net/snorri/landnama.htm
Chapter 31 Auðun married Mýrúna, daughter of Maddad the King of Ireland.
Mýrún Maddaðardóttir is said to have been been born in ( 870) the daughter of an Irish king.
She was married to Auðunn "stoti" Válason according to the book of settlements. That is not the same Mýrún/ Mýrúna as the one that was the daughter of Madach.
on her profile here on geni she is said to be the daughter of Bjaðmak (Beadh-mac ( Maddad)
Okay, so step by step:
1. On Geni, your profile for her [[Myrun Maddaðardóttur Bjadmakdotter Myrun Maddaðardóttur Bjadmakdotter] is definitely placed as the daughter of Madach, 1st Earl of Atholl not Bjaðmak (Beadh-mac ( Maddad). [[Bjadmak, King in Ireland Bjadmak, King in Ireland] So, this is the one we're looking at. (Although both seem - rather too coincidentally? - to have been married to an Audun, and both have a father whose name is Maddad - cf Myrun Maddaðardóttur Bjadmakdotter ]
2. Problem: The Earl of Atholl is Scots, not Irish
3. Problem: The Irish don't seem to know about Bjadmak, King in Ireland or Beadh-mac as one of their kings / nobles. Is it a reference to Macbeth, King of Scots ?
4. Problem: Macbeth isn't Irish either, and his dates are way past 890
5 RE mýrúna and margrethe as same person. What evidence that the names are interchangeable? Caithness certainly isn't interchangeable with Atholl, and, again - neither are in Ireland.
I have corrected the profile of Myrun. .
who is born In 870 and according to the book of settlement is said to be the daughter of an Irish king named Maddad. She married Auðunn “stoti”
I do not where the source information on who this “ Beadh-mac (Maddad) (Bjadmak) king in Ireland” is supposed to be but I’ve contacted the manager of her profile for sources on that. I have removed the other Mýrún from maddach.
Disconnecting the relationship to Margaret de Caithness pending the provision of sources to use to reconnect.