
The bio dad is really reckless. He should let her stay SAFELY at the duchy and let her be part of the duke's family while he dethrones the Empress. No wonder he has no power when he reacts with emotion and no plans. He would've also partnered up with the Duke to take the Empress down but instead is making him an enemy.
He also sees how she doesn't like him or the brother. Maybe try to slow be part of her life instead of forcing it.