GF has BAD acid reflux, and has been through a lot to get to the point where she is not suffering every day from it. I also have had problems with it, but not as badly.
I know everybody with GERD is different -- people have different triggers. For my GF, as for many sufferers, tomato sauce and coffee are big problems for her. She also stays away from most fruits (since they are so acidic), anything carbonated, and of course alcohol (though one would hope that would not be an issue for your dd

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She has found that she can enjoy all of these things in moderation -- she just tries to keep track of how much of the "bad" foods she's had during a given week. For example, if she were to have coffee every day or even a couple of times a week, that would be too much, but she has found that she can drink an espresso drink with half a shot of espresso two or three times a week with no problem. She also looks for substitutes for the foods she loves -- for example, pesto sauce on pasta is great instead of red sauce, and chai is great instead of coffee.
One thing I have read a lot about is that fatty foods can be a big trigger for some people. GF does not tend to have trouble with them, but many people do. Anything high-fat or fried can cause problems, so your DD may want to try switching to a lower fat diet to see if that helps her.
Finally, GF has had a lot of success by making sure she eats small frequent meals. A large meal can cause a lot of problems with GERD, but surprisingly, having no food in the stomach can also cause a lot of suffering. Granola bars, crackers, and other "neutral" foods are great to carry around so that you can make sure to have something in your stomach at all times. GF even finds that drinking plain water or taking a pill or having a tiny bite of something can really mess things up if her stomach is empty. She likes to eat something like crackers before taking her meds or drinking water or anything.
Hope that helps -- best of luck to her.