Oh yes that is another fun one :) I'm unsurprisingly more familiar with European medieval dynasties, but yeah there was a lot of intermarrying too. And many kids sometimes, though iirc fewer than in Japan, probably because men weren't allowed official consorts of concubines because of Christianity. Still many sometimes - Maria Theresia gave birth to 16 children while ruling an Empire!
Also, the most annoying name changes were when guys were "promoted" from duke to king to emperor and the number after their name changed, e.g. I once had to do a presentation for school on a guy who started Friedrich III, then became Friedrich II, ended up Friedrich I, and the specific numbers were coincidence but fun.
While in Japan people changed their entire names! Multiple times, even! Fun times.