Just a small piece of advice...be careful if you choose to try this though or it could actually backfire.
My siblings and I had lots of issues with the WTS but we believed firmly that it was the truth. I can see now that my Dad tried to do this with us at several points when we did have a family study (It wasn't a regular thing because my mother would stop it when he went 'off course' with the material. But his points were too on the mark and made us all squirm, and the looks from Mom at him would've vaporized him on the spot if it were possible to make someone vanish with a thought.
It mobilized the rest of the family against him and closer to the org. I finally got out later but they still have the rest of the family trapped. It delayed me for years, him bringing the ideas to me when I was already a confused teenager lacking guidance. I remember once actually going to my Dad with my bible and trying to explain why he had mistaken ideas. I couldn't explain away his solid reasoning though and it bothered me to the core. I was devestated thinking that he didn't trust Jehovah and that being the case, I couldn't trust him (I already had trust issues with him from childhood.) I went to the elders after that conversation, I was 17, and said that I was afraid my dad had apostate views, what could I do to help him? They told me they were aware of his attitude and because he didn't attend meetings that they wouldn't talk to him or do anything. They said that I should not discuss spiritual things with him anymore, and I went to meetings on my own after that for a very long time, determined that I had to stay closer to the org. because there was a bad influence in the house.
Funny I don't think about that often. I wasn't angry or snotty to him at all I was genuinely terrified for his salvation.
My dad is still technically in the org; he's inactive now but still believe's Jah's day is coming. Don't get him started on the GB though....his views and mine are the same on quite a few points. He has no issue, really, with me leaving the cult except fear that I might die when Armageddon comes. Though his theory is that god won't lose any of his 'real' sheep and that there will be a lot of surprises who is there and who isn't in the end.
So to sum up, I don't mean to throw cold water on your thread or your idea of using the family study...just that you have to be extremely careful. If children have been successfully indoctrinated up to that point...the reaction could totally backfire and delay for years their finding out the truth about the truth. That's what happened in my case, but your mileage may vary. People have got to be ready for it,
hugs
essie