NIC Fraternities and NPC Sororities have different rules regarding graduate membership.

If I'm not mistaken, only a few NPC sororities allow graduate membership. The others require that the members must be undergraduates.

Please do a search on GC for graduate membership, and it should bring up which sororities allow it. You might want to research Alumnae Initiation as well. ETA: I just wanted to clarify that graduate membership and AI are two totally different processes unrelated to each other.

Good luck.