While probably most of you know full well how Bretonnian Lords find the mercenary practice dishonorable and a waste of money, I still decided to give these units to Bretonnia too.
I changed their name from mercenary to Auxiliary for Bretonnia only, this should fix things lorewise.
I decided to make the Bretonnia Update mainly because there are some positive diplomatic and military events between Dwarfs and Bretonnia in lore.
It stated that during the Dark Age of Bretonnia (900 to 977 IC) a strong friendship between Bretonnia and the Dwarfs of the Grey Mountains was formed.
Also, quoting Darthon Ironbeard, Dwarflord of the Grey Mountains: "The Bretonnians? Aye, I know 'em. Arrogant lot, full of fancy ideas about valour and chivalry and what not. Yet they've no love for the grobi, mind you, so that makes 'em a firm friend to the Dawi!"
There Is also another episode during The Crusades against Araby (1448 to 1451 IC) in which a crusading force guided by Baron Tybalt managed to killed a lot of Greenskin armies along the way, forging a strong bond with the Karaz Ankor as a result.
All in all it's not much but for me Is enough to grant Dwarf units to Bretonnia.