NN Suthen's father Beornsson

Sibylla or Suthen's father (or mother) must have been a sibling of Bjørn Beornsson:

2. [sibling of Bjørn Bearsson]

[--- . m ---.] One child:

a) [SIBYLLA] .

The Chronicle of John of Fordun records that the mother of Malcolm and Donald Bane, Duncan´s sons, was "the cousin of Earl Siward"[384]. In one earlier king list, King Malcolm III's mother is named "Suthen"[385].

m ([1030]%29 DUNCAN King of Strathclyde, son of CRINAN "the Thane" Mormaer of Atholl & his wife Bethoc of the Scots ([1001]-killed in battle either Bothganowan/Pitgaveny, near Elgin, or Burghead 14 Aug 1040, bur Isle of Iona). He succeeded in 1034 as DUNCAN I King of Scotland.]

http://fmg.ac/Projects/MedLands/ENGLAND,%20AngloSaxon%20nobility.ht...