Definition of dependent is generally limited to spouse and child (not grandchild except in special circumstances); she needs to check because you would not want expenses to be denied.
Also, depending on school system, she might not be admitted into your school of choice; some are very strict on enrollment of students not in attendance area (ask me how I know this!!) which might be the case with an international student. Be sure everything is clear and in writing if there is any possibility there might be enrollment issues once she arrives. Also, be sure to have list of required documents (birth certificate, immunization records, school records, etc.) and translation requirements. Inquire about ESL classes if she is not functional in classroom in English. I expect she has had some English instruction already.
You might also inquire if there are any summer programs for English language learners or academic programs in the district and see if she can arrive in time for those. Remember also the entry date for students is a month (as I recall) before the start of school so she can be settled.
Good luck to you all.

