policies on legacies?

It's not a Bama thing or a chapter thing, it's dictated by nationals. You or your sister can easily find out the legacy policy for her sorority. A whole lot of nationals have dropped the legacy courtesy rule, which assured an invitation back to the second round, and placement on the first bid list if she made it to pref. No longer. It would still matter at Bama if your sister were a member of the Bama chapter, but her being from another chapter isn't of any interest at all. With that said, connections matter, so you may have some of those if you're from the South from you or your sister's friends and friends of friends from school or church or camp or whatever. Try to work those at all houses. Good luck