My 51 year old clan leader died leaving only four daughters and no sons. The (70 years old) kokujin of a neighboring province inherited the clan and the former leader's titles. This is all fine and well, except since he has no children at all (despite having four wives!) he has no real heir either. His heir is a random courtier to one of the other daimyos, for whatever reason, and as a result I cannot nominate him to be clan heir. I decided the only thing I could do was assassinate him, which was supposedly successful, except not only did he not die, but when my clan leader died a few days later, he took over as ruler of my five provinces and clan rule passed to someone else. To make matters worse, he is unmarried, childless, and 68, as is his heir. I've got 2 autosaves, which is not far back enough to resurrect my original leader, but given those two years, what could be done?