Since it has been a couple of weeks since you asked this, I am guessing you have your answer. But for anyone else reading this, yes, scoliosis can definitely affect headaches. They may not be true migraines though. Often, as with myself, the curvature of the upper spine will cause what the doctors call a "tension headache". This does NOT mean that regular stress or emotional tension is causing the pain. It means that,
literally, muscular tension from the back, spine, neck, and muscles over the scull cause the head to hurt. It doesn't mean that it isn't painful. It is. It is just a different set of symptoms, and causes. I happen to experience both tension and migraine headaches.
Your daughter is young for a bad scoliosis. Most people by the time they are in their 30s have a certain amount of scoliosis, or curving of the spine, due to some arthritis and aging.
Another thing that is at issue for females is that hormones released before menstruation can cause a migraine. Teenage years are often when those type of headaches begin. In fact, in the migraine pie of percentages, two thirds of sufferers are female. Estrogen and progesterone can cause this in many women young and older.