Posting for a sibling

Hello,
I recently posted a thread in which I requested admissions chances for my younger sibling, who had requested that I do so. This post was removed by a moderator that stated that posting for a sibling(or anyone who is not yourself or a dependent) was not allowed. I have not found anywhere that explicitly says that this is not allowed. Would anyone be able to point me in the direction of where this is explicitly stated?

Sure.
http://talk.qa.collegeconfidential.com/parents-forum/2090892-reminder-please-post-threads-for-yourself-or-your-children-only.html

As I stated when I closed your original thread, your sister is more than welcome to open an account to ask her own questions.