Olga Timeline and Summary

After grading papers, Olga hosts Irina's birthday party. She's got to look out for her baby sis, after all.
During the party, she kind of hangs out but isn't the life of the party or anything. Her drama certainly isn't at the center of the party.
An act later, Olga comes home late on carnival night, exhausted from filling in for the headmistress. Guess she doesn't like her job much, either.
Andrey lost a lot of money gambling. Olga is concerned about this.
After the fire, Olga helps organize clothes and other help for the victims. She may be a schoolmarm, but this lady's compassionate.
She gets into it with Natasha over whether to care for Anfisa (the old servant) or to get rid of her. Olga is all about keeping her on.
Olga advises Irina to marry the baron. It's okay that she doesn't love him, because that's just how the cookie crumbles.
Now headmistress, Olga takes Anfisa to live with her. She's not thrilled about it, but that's what you get.
As her own expression of regret during the moment the sisters share at the end, she cries, "If only we knew!" Which means that the audience automatically thinks the same.