Are these dialogues OK?

Person A - Is she there?
Person B - She's not here. If she were here, I would see her.

Person A - Did she come there yesterday?
Person B - No, she didn't . If she had come, I would have seen her.

Question

Are these dialogues OK?

Person A   - Is she there?
Person B   - She's not here. If she were here, I would see her.

Person A   - Did she come there yesterday?
Person B   - No, she didn't . If she had come, I would have seen her.

Answer

No

There are various possibilities but natural to me would be something like:

Is she there?
No she isn’t. I haven’t seen her anyway. 
Was she there yesterday?
No she wasn’t. If she had been, I would have seen her.

Answer

1.B. No, she's not here. If she were here, I would have seen her.

2. A. Did she come here yesterday? Etc.

Answer

Yes