How to respond to negative relatives
One thing that many have found useful is blitzing relatives with information. Tell them you'd be glad to discuss it once they've done their homework and once you have a common ground of information to work from.
I don't so much care what they think, but at the same time I never have any snappy comeback.
I said this a few times, in such cases, when Kirby was little:
Well, if this stops working, we'll put him in school.
Those relatives and friends have a couple of motivations when they say what they say. They want to comfort themselves with assurance (all involving the voice in their heads, and the children they once were) that school was good for them in some way, that they didn't go to school for nothing. You're coming dangerously close to causing them to have to review everything in their whole lives and they don't want to do do that. The other thing they want to feel better about is that you haven't gone totally insane, and so if you say "If this doesn't work, we'll put him in school," they will feel that you're constantly assessing the situation and that school IS an option for you, and that maybe they will have their own nervous fears soothed in the end, and that THEY (not you) will get to say "I told you so."
Let them have that little hope. It will keep them calmer and quieter, and it will also probably make them more likely to really look at your kids not in the light of their being lost forever, but as possible future schoolkids. It costs you nothing, and defuses the hostility.
I don't have ONE relation who is interested in what we really do. Don't any of you think that others would be interested in discussing with you unschooling or just the fact that you live your life a little differently?
What if one of your children grew up, had a family and started involving her family in a cult you'd heard scary things about? Her happiness and confidence might give you the impression she's still rational, but why would she be making such irrational, scary and "obviously" wrong decisions?
How much would you be interested in what she was doing with the cult? If you already knew it was bad, wouldn't anything she said sound like brainwashing? On the other hand, how much would you be interested in hearing comforting words that she was coming to her senses and thinking straight again?
They're fishing for those comforting words because they're scared. Everything they're certain of about what kids need -- and society confirms it for them -- you're apparently oblivious to.
I liked Susan's answer about blitzing them with what the kids are doing. :-) That way you aren't allowing yourself to take a defensive position and proving you're right. You just blaze on ahead with full knowledge that you are right :-)
Another tactic is to give them information to read and say you'll be glad to discuss it when they're done reading.
It seems my brother in law has already decided his son is not going to come around my kids anymore, and when my boys saw their uncle they got 50 questions shoved down their throat.
It's good that he's going to stay away so they aren't bombarded with 50 questions! If he does break his word and questions them, you can tell him not to corner the kids any more. If he has questions to ask you.
He's probably scared and feels threatened by your decision. That might help you see his behavior in a new light. (Understanding doesn't mean you need to put up with it, though!) He is probably terrified that getting kids to turn out right and getting them what they need is just so chancy that anything that makes him question the choices he's making for them is going to be upsetting. Basically people who send their kids to school have to trust that the school can give kids what they need. Most people have a decent amount of confidence that it is so. But if someone feels their confidence rattled (say by troubling reports of schools) and that the alternatives to school are even worse -- if experts are doing such a poor job, then what does that say for amateurs like mothers trying to teach their kids! -- then they have to stuff their fears down and just hope for the best.
By your homeschooling you're throwing it in his face that you're so lacking confidence in schools that you're willing to do it yourself, despite a lack of professional training. Your actions are letting his fears come to the surface and he doesn't want that. He wants to keep them stuffed down because facing them is overwhelming and something he doesn't feel he has the ability to tackle.