There is a lot of ideas that come to my minde after seeing your replies. And I think that it would be very interesting how to families or clans or whatever come together and join into the same. The idea of heraldry would put too much in the game for I think we know how heraldry was an "art" or "science"; so yeah, I kind of dig all those points that it is kind of complicated and all that, but it is also somehow necessary to keep up a lineal or historical lineage of the clans and relations that might happen during the game.
Nevertheless, a mod can always add something useful and important, but the idea of heraldry should at least be considered.