It is a better option to go national if your school's activities director is concerned about liability. All NPC sororities are incorporated and have policies prohibiting hazing, prohibiting alcohol on sorority premises, requiring a third-party vendor for alcohol at sorority events, etc. I'm not saying your local doesn't have similar rules, but a national body overseeing the chapter can only be a good thing from a liability standpoint, as far as the activities director is concerned.
Since there are no NPC orgs currently represented at your campus, your sorority and your school's activities director can approach NPC directly. If you have a preference for a particular NPC org, you can indicate that when you approach NPC.
BTW, I'm a founder of my chapter of AEPhi, and we started out as a local sorority called Sigma Iota Phi. So your letters make me smile
