Your sister needs to file a request for an order of protection, Monday Morning With the local police! !!! Don't even bother calling WTBTS. An order of protection is better than a restraining order. If they break an "order of protection" the elders can personally can go to jail. They cannot visit her house uninvited, this is stalking. She needs to get their names, addressees and phone numbers if possible, or as much information about the elders/ stalkers for the written complaint and request for an order of protection. HINT: Google and other search engines, even Facebook, are a great providers of addresses phone numbers and birthays, and other information needed in filing out an order of protection.
If she files for a restraining order or even better an order of protection she will most likely get it, but if they deny visiting her house, she will need a photo or some proof. If she explains to a judge what they are doing, they will have to lie to get out of it. Judges today will err on the side of the accuser. Proof via Camera phones' photo is acceptable.
I can almost guarantee that if she files for an order of protection against the elders individually, she will never face the committee for the accusations of apostasy. The elders are instructed to drop the pursuit mode if inactive people even hint at legal repercussions. Hope this helps.
File the order of protection on the individuals NOT the congregation or WTBTS.