I sure hope you're right about them taking this situation seriously. Your DD deserves to have her needs taken seriously, and you deserve to have your wishes taken seriously. But, even with them taking it seriously, they probably have different ideas of what this means.
To me, it sounds like you want subject acceleration, not differentiation and enrichment. It sounds like you've spent a year trying it and it didn't work. A year is a long time in the life of your DD.
If I were you, I'd take this tack (and I have): teaching is difficult, teaching to a wide range of abilities and personalities is difficult. Asking a teacher to accommodate your one student is unreasonable. At least, it is unreasonable to ask a teacher to do it consistently throughout the year. It is unfair to the teacher to have to take her focus away so often from the rest of the class. You sympathize with the difficult situation teachers are in. And you think subject acceleration will help both your DD and her teachers. Subject acceleration will allow your DD to be in a class where the teacher will not have to treat your DD any differently than the rest of his or her students. There will be no extra work for the teacher. Now, secretly (or not) the school administrators will worry that your DD is not emotionally ready to handle this and that your DD will take extra attention in the higher grade. Do whatever you can to allay their fears.
Go into your meeting optimistic that they have the best interests of your DD at heart. They might. But, be prepared to ask for what you truly want and feel is best and stick to your guns. You don't want enrichment. You want subject acceleration. You know your DD best, both as a person and as a student. You're a smart person and you have a reasonable request. Don't falter in your convictions.
If they are still hesitant after you making your case, do what Grinity often suggests and offer to sign a waiver saying that you take full responsibility for any negative outcomes if the subject acceleration doesn't work.
Good luck!
