<p>If you are US Citizens then you should give your US address, however you should give your actual address once she enrolls, so that the school is able to communicate with you.
If you move around a lot, then a boarding school experience will bring her stability in friends that teens crave, and that she probably isnt getting. Also besides the absolutely outstanding education that good boarding schools provide, she will have the benefit of continuous classes and teachers that will know her, her learning style and habits that can help her in case of issues (and will be able to write a knowledgeable rec for college)</p>