May I humbly suggest that the best/only way to combat bad ideas is with better ones?
The "training" one gets from the Watchtower is simply organized bad ideas, irrational thinking and superstition.
You overcome all that by teaching critical thinking to your kids.
You can avoid belittling your wife or her efforts by being really matter-of-fact and non-confrontational.
The trap (and it is a HUGE TRAP) comes from trying to get down in the same mud as the Watchtower and fighting on their turf.
Religious ideas are emotionally connected links.
The links are connected to things people want or fear.
We fear death and religion links everlasting life promises.
We desire approval and religion gives us Divine approval IF we accept everything we are told.
You can easily demonstrate how invisible and fluffy each of these things actually is by appealing to the commons sense bullshit detector every child has.
Christianity pretends what it has is a product and brand that is superior to all others.
What it doesn't want you doing is product research behind those claims.
Show your kids how you do research to check the claims.
Contrast how science works with how religion comes up with its "facts".
Science tries to disprove its own claims by applying critical skills and falsifiability. Religion makes claims and pushes the Authority aspect.
To be skeptical and test things in science is a virtue. In religion it is a lack of "faith" and disloyal and perhaps heresy.
Point out the history of the Inquisition, the bookburnings and censorship of ideas religion has fostered out of fear of free expression.
Show how science and religion have clashed and how all progress was IN SPITE OF censorship and authoritarian disapproval.
See what I mean? Be a good teacher and let their rational minds flourish.
Religion denies us our right to reality by pretending to another and better super-reality.
We all have a right to reality.
Give your children a healthy dose and they will choose the healthy way (mental health!) to go every time.