So she is up and awake when she is pooping?

Maybe I am wrong in saying this but I think it is time to get angry and give punishment. If she is doing it in her diaper while fully awake and conscious of what she is doing then you need to get on her. She knows better.

Have you talked to the doctor about her peeing at night? I would limit fluids after supper and take her to the bathroom before bed. Also don't ask, just tell her to go. The second you get up in the morning it is straight to the toilet.