Hi Q.E.,
The links I posted in my first post are a good place to start. There is much info on the group with accounts of how to get someone out of it.
There appears to be two mind control dynamics present with some "Way"people. There is the usual indoctrinationation and threats upon leaving as you have mentioned that exist in theses cult like fundamentalist Churches plus also some of the followers go to the Momentus LGAT training. There is readings on that in the links I have provided but basically it is similar to Lifespring and Landmark.
One way of dealing with cultic abuse is to work with the person in respect to their original belief systems. You mentioned that you were/are Catholic. Can I presume your sister was too before joining the Way? I have been reading about another person who is anxious to get her frineds out of the "Way" in a Catholic forum called Catholic Answers. There is some interesting reading from a Catholic perspective on the Way and some people have offered apologetic answers to the indoctination of the Way. The doctrine of The Way appears not to be Christian all though the Way claim they are. With there being origins of Catholicism in your situation, I see it as fitting to pass to you Catholic repsponses to the "Way" problem.
Here is the thread:
[b:20429cc493]Catholic Answers:
"The Way" is trying to recruit me and my husband[/b:20429cc493]
[
forums.catholic.com]
One final point. The Way told you that if you leave, you will be going to the Devil. You don't believe that anymore, do you?
Oz