The princesses dissapear (or don't appear) at 16 if you agree to a marriage proposal the turn she hits 16, then she's married to the general.

Bit dissapointed with the princesses on the faction heir marriage front ... the ingame help says something about watching if the first child of the union but from reading on the forum it seems they make no difference boy or girl. (both political marriages i've had gave girls as first born)

No civil wars