CrusaderKings

The baby 's emperor will not become a new heir because I had to get a sacred Roman emperor on the throne of Byzantine (fortunately he was the next person to inherit the Byzantine Empire) ). Then I pressed my heir's wife's demand for the Byzantine Empire (she received a strong request a generation ago), and she and my successor killed her after having a boy. Then, generation (I play my grandchild) I pushed my argument

I got the Holy Roman Emperor because I was being asserted about HRE. That meant that I could get everything soon, but the plan would never go wrong. (Even if it is very convenient)