Reflecting a bit more on the Houses' names, Toulouse could perhaps be Aquitaine although it would need to unite with Bordeaux to fully bear its historical name much as Reims will have to get Metz before fully becoming Lorraine...

This would give us

Bretagne (Rennes)/ Aquitaine(or Navarre) (Toulouse)/ Bourgogne (Dijon)/ Lorraine (Reims)