Heres the thing. Back in those days the idea of a woman ruling was unheard of. The Baron's daughter would not be the leader of the land by inheritance or anything. Heck she probably wouldn't even have a choice in husband.
We saw a smaller scale version in Weirdwood. Victoria neaded MC to run for mayor cause there was no way she was going to officially be allowed. If Cath & BD is the same person it makes sense. She seduced Roderick (& probably done so with other strong, well connected men) to unite the bandits. Probably promising things she dosent intend to keep.
That's why I said she'd marry a controllable husband... she'll rule through him as her marionette.
Similiar how Victoria became the "Mayor" of weirdwood.
And again as a daugther she has the legal claim for her family to inherit her fathers title, it's overkill to undermine your own authority if you take over afterwards anyway.
She can play the loyal daughter, until she offs her father & takes the Realm by force. She would need strong holds over the surrounding towns because if the Capitel cought wind of her treachery then they will kost likely send a garrison to bring her down.
The capital is unlikely to intervene in a power squabble of minor nobility unless it threatens it's borders and influence.
Noone wants to rule the backwater provinces anyway.
She could be a different person but I beleive this could be a more interesting story route. For example: if you play along & help her, MC might be able to set things up so she is a "stand in noble" until she marries. Then a "noble from another realm" (*MC*) arrives & marries her becoming the new "Baron" while she runs the country.
"Then a "noble from another realm" (*MC*)" THAT would be an Event that would trigger the interference from the capital as it would mean a risk to loose controll of that land and it's resources, without any certification of his nobility he wouldn't be announced a Baron aswell.
Wether or not there the same I just have a strong suspicion Cath is the daughter.
Maybe an illegitimate one with a Maid but none that is in line of succession