I haven't tried this yet but it might be interesting to see how it works. For role-playing purposes, pick one family member and "play" him throughout the campaign (until he dies, of course).
This means: only fight the battles that he commands, only manage the settlements that he manages. Diplomatic, spying and assassination mission should not be restricted but always carry a diplomat and a spy (and an assassin too if that's how you like it) as the "Basileus' own".
If you want to go hard-core, give him an army and stick to that one for the duration of play.
It would be my version of a "Megas Alexandros" campaign.
Damn... now that I think about it, I'm going to try it and write an AAR from that.
Edit: Additionally, he doesn't have to be faction leader and if he isn't, you can limit his resources, decision-making authority, etc.
I know, now I'm just blabbering.
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