@Louzan It might be intentional though. As in "she doesn't hold the title herself, she's merely stewarding it for her adoptive children until they come of age and take it over, and she never did hold the title either".
Granted, in most cases she'd then be a marchioness - but ours is a world that rarely allowed women to own their own titles, so it would always be assumed that a marchioness was "merely" the wife of a marquess (or marquis - which is how I learned how to spell it, I only just now realized they were exactly the same).