Just a suggestion - does the priest / vicar at your own Church have any ideas? Sometimes they have come across JW's, or they know someone "clever" who you can talk to, to help you refute their arguments.
My ex-husband (non-JW) would not let me take our son anywhere NEAR a KH when I first got "involved" with them. (Quote - "you take him anywhere near that place or those loonies and I'll take him abroad").
I am so glad now, even though I was furious at the time (I've wised-up since). My ex used to grill our son to find out what I'd been telling him, so fortunately I daren't tell him much, because I wanted to spare the poor lad (he was only 7 at the time) from his Dad's grillings.
I'm a teacher and I always think the best thing you can do for the kids is teach them to QUESTION EVERYTHING, especially what teachers tell you, because they're all fruit and nut-cases.....!
It sounds to me like you are doing all the right things.
Good Luck and God Bless.
Jules.