It depends on that school's population and, to some degree, your ethnicity. The schools have to comply with federally mandated desegregation guidelines, which limit the number of black students at any school. So if you are black and want to go to a school that already has the maximum number of black students, then you are out of luck. There are few exceptions. If you are white and apply to that same school, then chances are good that you'll get in.
Siblings get no special treatment.
The remainder are being processed. You can appeal to the SAP Appeals Committee, but its decision is final. You must abide by those admission procedures. You can select a school with a particular curriculum or environment. Permits may be difficult to obtain.