Moving abroad beginning of Junior year in HS?

[Sybylla]

      The devil is always in the details. Companies can be great, or shady, with relo deals. The issue is often more naivete than anything though, and knowing what to demand. The romantic grand adventure is always exciting until you lose money on your house, cars, university fees, etc. If this was the UK, I expect this wouldn't be a thread. If it was Mongolia,, there are wrinkles to be ironed. 

[MYOS1634]

Where will you be relocating?
Are there important differences (dictatorship/authoritarian state, street violence, no separation between ‘church’ and state, men/women equality, significant poverty, “compounds” for foreigners…?) that may be a problem to discuss ahead of time and might present obstacles?
Are you in contact with families there? Will your company help with relocation beside moving your stuff?

Be aware that in some countries, a girl playing hockey may have trouble finding a team, or that hockey may not be wel-known at all. You could approach the principal right now (before the move) to see how open the school would be to your daughter creating a co-ed hockey team, or if there’s no ice rink a co-ed field hockey team? This way she not only would be captain, but also would get to teach her skills and share her enthusiasm.

All in all it’ll likely be a mind-opening experience for all.

Choose IB courses carefully: some courses (Math, Physics) at HL level are extremely strenuous.
Taking the country’s language as an SL ab initio will be a great way for your daughter to get external validation for what she’s learning out of school.

[Kardinalschnitt]

My elder dd is currently at the type of school you are considering. You can PM with me questions if you’d like.

[Consolation]

I gather that the OP is an Illinois resident. Here are the relevant regulations:

F. The minor children of persons who, having resided in this state for at least twelve months immediately prior to such a transfer, are transferred by their employers to some location outside the United States shall be considered as Illinois residents for purposes of the computation and payment of tuition. **However, this Section shall apply only when the minor children of such parents enroll in a state-supported Illinois college or university within five years from the time their parents are transferred to some location outside the United States. ** [Note: The University of Illinois Act (110 ILCS 305/7f(a)) defines “Illinois college or university” as “the University of Illinois, Southern Illinois University, Chicago State University, Eastern Illinois University, Governors State University, Northeastern Illinois University, Illinois State University, Northern Illinois University, and Western Illinois University.” These are the same institutions covered in this Section and in Section K below.]

If the parent(s) or legal guardian of a resident person establishes a domicile outside the state of Illinois after the person has been admitted, the person shall continue to be classified as a resident student until degree completion, assuming timely matriculation and providing the person maintains continuous enrollment and maintains a separate residence within the state of Illinois.

G. It is required that a person who claims Illinois domicile while living in another state or country will provide proof of the continued Illinois domicile. Proof may include, but is not limited to, evidence that the person (or parent or legal guardian as applicable) has not acquired a domicile in another state, has maintained a continuous voting record in Illinois, and has filed regular Illinois resident state income tax returns during absence from the state.

Sounds to me as if it should not be a problem.

I find it highly unlikely that an IB school catering to expat Americans would be unable to provide appropriate support for US college admissions.

Seize the opportunity!