Complex sentence: If a girl faces a looming forced marriage she can (if she wishes) file a declaration with her school, and the school must notify police if she does not return after summer break; a forced stay abroad can be fought legally with such a declaration.
Split into simpler sentences: If a girl faces a looming forced marriage, the girl can, if she wants, provide a declaration to the school, and the school must legally notify police if she does not return after summer break. A forced stay abroad can be fought legally with such a declaration.