What purposes are served by the appearance of Antigone and Ismene in the Exodus?

The purpose of Antigone and Ismene's inclusion in the Exodus, illustrates the longlasting effects of Oedipus' actions. His daughter couldn't help their births...... they were innocents, but they were also connections to the future. The girls cannot protect themselves, thus, Oedipus asks his brother to protect them. The girls love their father..... and he returns their love. Oedipus is destined to live out his life as an outcast...... and his daughters will be shunned. His daughters give him a reason to go on..... a reason to live. Though he is now blind..... he truly sees for the first time.

"Such a disgrace, and you must bear it all!"