To start this discussion, take a look at George School. (Boarding school with day students). It’s grounds abut Newtown Friends School - day, K-8, and it is also in an excellent public district. There are a number of kids who are serious musicians who participate in school ensembles and many have teachers in Philadelphia (or NYC). Nice, kind, inclusive environment that would value the international experienceyour D would bring. There’s a learning center, but there are other schools that are stronger for kids who need more structure and/or supports. IB program is strong and a good option for students who want to go to college abroad. It’d be helpful to know what learning supports are needed as these vary enormously from school to school.
Any school near Boston will have good music options outside school. If you like George School’s schedule, look at Cambridge School of Weston. Tons of great public districts in the area.
Both of those two are a bit easier to get into, which may matter as you try to plan around so many moving parts.
Hotchkiss has an excellent music program and a more traditional curriculum/schedule. It’d be a bit harder to participate in non-school music activity from this school, but it’s top notch by all measures. It might be tougher for a kid with learning differences.
Walnut Hill specializes in performing arts.
It’s in a “school -rich” area so you wouldn’t have to choose it for both girls.
Why not look at these and let us know how these align and we can offer ideas from there.