As we have it at the moment, Bartolf de Leslie is given as the founder of the clan Leslie, and the source from which this comes (it's the clan Leslie story) is that he was married to Beatrix, the daughter of Duncan, king of Scotland.
Problems with this:
Medlands (and wikipedia, for that matter) give Duncan three sons. Period, No Beatrice.
Here's Medlands on Duncan, with Beatrice not showing up: https://fmg.ac/Projects/MedLands/SCOTLAND.htm#DuncanIdied1040B
The Overview for Bartolf gives us the story as above, as given by the Clan Leslie historian -- but there are no citations of source documents.
The archived Clan Leslie site gives the same story, but no documentation -- https://web.archive.org/web/20170813143814/http://www.clanleslietru...
And I got there by looking up Bartolf Leslie in wikipedia, which handily sent me to the Clan Leslie material, and said he was married to Princess Beatrice, EVEN THOUGH the King Duncan wikipedia page does not say she existed.
However!
There exists a collection of historical records of the Leslie family, and snippets that I can see on the web say that the Beatrix information comes from 1792, John Brown, Genealogist of Scotland to the Prince of Wales, and he says that Beatrix married Bartolf.
Ok.
Nowhere am I seeing any evidence of sources, but the Scottish genealogist is important -- and would be the seal for this information.
So, unless somebody has something that Medlands doesn't have, I would think that we need to connect Beatrix of Scotland to Duncan, AND give notes explaining the situation.
Unless somebody has evidence that John Brown can safely be ignored.