And here is a sneak peak of the overall change of the family tree. What I wanted was to give even more gravity to the non playable royal line and possibly allow a degree of managing or at least knowing its members better. And of course....Herakles! The bloodline of both kings will lead all the way back to Herakles. It's almost done btw. The red wreath on the portraits means different political party.
But I have a question now. I experimented with changing the playable party from Agiads to Eurypontids (since the latter seem a lot more active militarily during the period) but then the party leader of the Agiads doesn't become Pleistoanax but his son Pausanias.
Is there a way to pick a different party leader for non playable parties? Gravitas or ambition doesn't seem to affect the game's decision of who the party leader should be.