Is this legal? Deactivated one NPC, now part of a new NPC.

[SWTXBelle]

The student has to be registered at the college in order to pledge. Colleges routinely use s.s.n.s to identify students - I always have to provide mine to get transcripts. I doubt that many students would lie about their s.s.n. to enroll in college - it would make it too difficult to get employment later. So, some means of cross-checking with the # is probably feasible.
Having said that, I don't think it is really that big of a problem. In this case, I would notify both NPC orgs. Perhaps her losing both memberships would be a good example!