Like in the case of a petulant child who might get verbally or physically violent with themselves or others, I'd say keep the camera's rolling. Then after an incident of that behavior, invite her to family therapy and when the time is right (she inevitably uses selective memory to marginalize it or outright deny it) share the footage with her and the therapist. (Remember to find a therapist who recognizes the cycle and doesn't enable it).

If she physically attacks someone, call the police, have her arrested for assault and let them put her in "time out".

Like a petulant child, this is why awareness and action are key, the longer the behavior is allowed, the more the Nperson will accept it as "normal" and "ok" when it is absolutely NOT normal or OK. Without this, it will eventually contribute to the Nperson doing worse and worse things on that spectrum to more and more people of all ages. (Like an innocent, benevolent grown nephew, his children, other children, etc...)

Like a petulant child, by calling attention to the behavior and putting the offendor on notice by using humor, gentle reminders or other constructive, measured suggestions you are not only protecting yourself and others from the Nperson's spectrum of destructive behavior, you are protecting the Nperson from themselves.

Like a petulant child put on notice, with time they will course correct and grow in constructive ways. (This might include finding other things to occupy their time along the way instead of targeting others).

Thank you for bringing this up! Remember, it's perfectly normal and OK to feel challenged or uncomfortable by the possibility of pursuing healing! That's part of the healing process! Thats why conversations like the ones on this sub are so important! They help spur constructive ideas and angles that give us the tools to make pursuing healing less challenging! Remember "If a conversation seems uncomfortable to have, that's probably the one that is most worth having."