Let's say hypothetically I would like to form the Tokugawa Shogunate starting as the Matsudaira Kokujin of Kamo. How would I go about leading a clan or defecting from the Hosokawa clan to one where I could be a direct vassal (and can later scheme to lead my own clan, obviously)? I've attached a few screenshots of the starting situation and how the diplo options that would let me defect or lead my own clan aren't available due to my vassalage status.