I think having a family tree for heirs kept to a more natural selection, like no adoptions.

Then making generals into nobles and awarding them titles as rewards.

I am not a big history buff but did queens come into reign during these eras?

I really hate having my family tree expand so big with adoptions and what not but I also need the generals so I usually do it.

I just wish they would have worked on this a bit instead of just using the same old RTW setup but even that allowed changing of heirs.