So very, very sad. And so, so frustrating - it's like hitting your head against a brick wall isn't it? I just hope and pray that conversations like these put little seeds of doubt in peoples minds and they are encouraged to look into these things for themselves, not just to believe everything churned out by the organisation.
The sad thing is that a just over a year ago I would have most probably shared her sentiments and responses, thank goodness I took it upon myself to open my eyes, become better informed, investigate my worries and concerns and I finally saw what the organisation was really about. I hope that this happens for your sister in law, it happened to me and I was pioneering at the time, very zealously too, so I thought... it could happen to her too. Don't give up hope.