Ok let's use an example:
- Let's imagine you want to add Epiphanes Platonos Soter to the game (a minor Bactrian ruler in RL - gotta love the guy who names himself both "God manifest" and "savior" at the same time). You create him via the txt file and attach him to Egypt. You set him to be born in 186 BC, to die in 136 BC.
Now:
1) If you start the game in 187 BC or earlier, you will not see this character in the game. All the cahracters born since the start of the game will be randomly generated.
2) If you start the game in 135 BC or later, you may find Platonos in the dynasty as a "dearly departed ancestor".
3) If you start the game between 186 BC and 136 BC, then Platonos will be there, alive and ready to serve any function you give him.
However, once you start the game the big random event machine starts rolling. If you start the game with Platonos alive in 180 BC, then in one game he may live longer than to 136 BC, but at other times he may die early. In one game he may marry and have many sons, in others he might end up childless. Once the game starts, its all going to be influenced by random events.