Tengo una pregunta por qué necesitas a tywin Lannister en el norte puedes también cosegir los mismo que en occidente sólo ofrecerles comida barata en invierno y listo bueno esa es mi opinión no se si estoy equivocado
You can get a commitment with the first daughter of the Starks (Sansa), you are the ruler of the Dominion and you can educate her with the Protestant Church.
All the Ladies believe in the Faith of the Seven and that would be a problem with your vassals (Prussian people). They fought a war for more than 20 years to defend what they believed in, they can wait a little longer.