I am a migraine sufferer and have had them since I was a child, I'm not a parent, but perhaps I can give you some perspective from someone who has experienced migraines from childhood to adulthood.
We didn't do anything about mine as a child and as a young adult they went away for a while but then came back in full force. As a young person I could withstand the pain and did my best to live a fairly normal live. Now that I've had them again for ten years, the last five years chronically nearly every day, I can't stand the pain anymore.
We've tried so many drugs, so many treatments and so many alternative therapies but nothing has worked. I've been to see neurologists, doctors, naturopaths, transpersonal psychologists, regular psychologists and another host of medical professionals. We exhausted so many treatments that I'm now taking narcotics. We're still looking because I would prefer not to be on narcotics but I just couldn't stand the pain anymore.
I wish we had found a treatment / solution when I was younger and could stand the pain. Or at least could modify my lifestyle so that it minimized my migraines. At 35 I am on disability and spend a lot of my time in bed suffering from migraines. I am lucky I have an understanding husband, but it easily could have gone the other way and I could have been divorced.
I also know I wouldn't have wanted a treatment forced on me, but perhaps discussing with your daughter the possibility of having migraines for the next 15, 25 or 35 years are worth figuring it out now to try and get her buy in.
PS At 35 my mom is now involved in helping me find the solution to my migraines. Unfortunately or fortunately your job is never done.