Why is it that a sister with a criminal record, (no matter how long ago) is not allowed visitation with a brother in prison?

Prisons get to set their own guidelines and restrictions, which can seem arbitrary and capricious. In general, so long as the policy is applied uniformly, these restrictions can be difficult to challenge.

Respectfully, this is not an issue that can be properly addressed on a site like Avvo.com, and needs the advice of an experienced criminal defense lawyer who probably has dealt with these type of situations before, just as I have here in NJ. I suggest that you either contact a lawyer you already know, or check out the Avvo listings of the lawyers admitted to practice law in GA, who practice criminal law. Good luck.

DISCLAIMER
This answer is not intended to, nor does it create, an attorney-client relationship. It is not intended to constitute either legal advice or attorney advertising. Instead, given the nature of this website, it is provided solely for informational purposes, for you to use as a starting point when speaking directly with a lawyer in your State. Do not assume that the legal theories I mention that pertain to NJ will apply in your State. The facts of each case are different, and it is therefore critical for you to consult with a qualified counsel with whom you can share information which can be assessed under an attorney-client privilege, so that you can get competent legal advice from which you can make informed decisions. I urge you to immediately contact an experienced criminal defense lawyer admitted to practice in your State before making any decisions about this case.