This is what DoDMERB and the waiver authorities are looking at for the disqualification for headaches:
"History of recurrent headaches, including, but not limited to, migraines and tension headaches that interfere with normal function in the past 3 years, or of such severity to require prescription medications, are disqualifying"
So in english, any headaches in the past 3 years that interfere with normal function (school, extracurricular activities, work) or that require prescription medication are disqualifying. There does not need to be a diagnosis of migraines or tension headaches associated with them.
You say your daughter was prescribed Topamax in the past, so this would be a disqualification from DoDMERB. Now its up to the waiver authorities to make the determination on whether this is going to be an issue for the next 24 years. You say she was prescribed in the past, if the past was last week, your daughter is going to have a difficult time getting a waiver. If the past was 2 years ago, and she has not had issues with headaches since then, and has not taken Topamax in that period as well (a headache every 6 months that she takes Tylenol for is not an issue), then the chances for a waiver go up.
Does this help?