I would question your doctor again. He's not listening to you... Don't think that is "night terrors" but perhaps a little bit of jealousy over her brother, and she knows how to get to mom...
Night Terrors Symptoms: Sudden awakening from sleep, persistent fear or terror that occurs at night, screaming, sweating, confusion, rapid heart rate, inability to explain what happened, usually no recall of "bad dreams" or nightmares, may have a vague sense of frightening images. Many people see spiders, snakes, animals or people in the room, are unable to fully awake, difficult to comfort, with no memory of the event on awakening the next day.
Night Terror or Nightmare?: Nightmares occur during the dream phase of sleep known as REM sleep. Most people enter the REM stage of sleep sometime after 90 minutes of sleep. The circumstances of the nightmare will frighten the sleeper, who usually will wake up with a vivid memory of a long movie-like dream. Night terrors, on the other hand, occur during a phase of deep non-REM sleep usually within an hour after the subject goes to bed. This is also known as stage 4. (A link to a sleep stages chart can be found on the navigation bar to the left) During a night terror, which may last anywhere from five to twenty minutes, the person is still asleep, although the sleepers eyes may be open. When the subject does wake up, they usually have no recollection of the episode other than a sense of fear. This, however, is not always the case. Quite a few people interviewed can remember portions of the night terror, and some remember the whole thing.
You mentioned a daughter, so I'm assuming she's young.