Thanks for sharing Julia.
I don't think there is a 'correct' way of handling these discussions, but the more I read these experiences, the more I feel it should always be reasoning from the WT.
The WT mags are so full of errors, contradictions and changes that I think I would take one point at a time and raise it. You don't even need to get an answer from them, just move from one to the next to the next, in the end it will be blindingly obvious that placing your trust in the WT is akin to building on sand.
Then you could drop in something like "where do these untruths come from that we have been teaching",
or "where in the Bible did the apostles teach wrong things, then change to more wrong things, then back to the original things?",
or w12 6/15 p.28 "Human advice is constantly revised and updated",
or w76 5/15 p.298 "What confidence can we put in the sincerity of or judgment of such [vacillating] persons?",
or Gal 2:18 "If the very things I once threw down I build up again, I demonstrate myself to be a transgressor",
or what did Jesus mean in Matt 12:37 "by your words you will be declared righteous or will be condemned"?,
or what constitutes the indecisive man in James 1:7-8 which says they will receive nothing from Jehovah?
or "how can I trust that what I'm being taught today, is actually 'truth', since I have been taught falshoods all my life?"
or, of course, Deut 18:20-22.
For each of these, do not allow yourself to be fobbed off or the topic redirected - keep returning to it, keep asking until they squirm.
If they dismiss it as being 'old', as in this case, remind them it was from Jehovah's channel - do they believe the FDS are Jehovah's channel? If so why would they dismiss something as old? The Bible is old, do we dismiss that?
One day in the future, todays teachings will be old. Will they dismiss these the same way as they are dismissing the other 'old' teachings? If so, why not just dismiss them right now?
There will be the inevitable statements like "even the apostles made mistakes", "the Truth doesn't change, only our understanding of it does", "it's better to make mistakes and stay on the watch, than fall asleep", "we need to follow the lead of the FDS", but knowing these are coming gives you time to prepare for them.
I think it's all about controlling the meeting - you deciding what topics are raised, dismissing anything else that is spoken about, and keeping to your agenda.
It sounds like it was very tough Julia - you did what you could in a difficult position - well done.
Splash.