Steve: Nothing. Whether physical or emotional, force is wrong. Olga should know this. If she doesn't respect your boundaries, she is not a good friend.
Mia: Asexuality is just as much of a thing as bisexuality, homosexuality, and heterosexuality. The Asexual Visibility and Education Network (asexuality.org) has some good material to point her to.
Mia: You should not ask her out, and she should make the first move. She is your subordinate, and that puts in her a weird position even if she wants to date you, because there might be a stigma that any company advancement came because of your relationship. But, look, if it's meant to be, it's meant to be. Be a good friend, be supportive, but don't make her feel like she has to date you.