How to get confessions at the meeting with HT and CT?
Well the first thing I suggest is to be ever so nice. It will be painful, I know, but people are always much more forthcoming when you are nice to them and flatter them a bit.
I am outraged at what is happening to dc, and have no doubt that it is the school's attitude that is at fault, but you need evidence, and being nice may be easiest way to get it.
If you want to give them enough rope to hang themselves with, then maybe going to the meetings with the line that you have heard that dcs can be phased if things are done differently at home and at school.
Then you might be able to say that as you know that they are the professionals and that they have the training, (flattery) and you are just a mum, you really want to hear exactly what techniques they are using, in case the distress that you are seeing in dc at home is because you are doing things differently at home. You could also feed them some guff about not wanting to rush into moving in case it makes no difference.
With luck, by now they will be thinking that at last you have seen the light that it is not the schools fault, it is all down to mum getting things wrong at home. In this mindset they may give up everything that they want you to hear. And be happy to amplify to answer your questions. Fingers crossed that is what happens.
Let them wax lyrical, and take copious notes. Write up a note of the meeting afterwards and send it to them.
You don't need to be drawn on whether you think they have been doing the right things, just say that you want to think about it and you will get back to them.
If what they say differs enormously from what dc is telling you, would you be able to check with others in dc's class - maybe via their parents?
If what they say fits with reality and is clearly the reason why ds is miserable, then bingo, you have the evidence. They will have had a note of the meeting and had a chance to comment if you have put anything down that is wrong.
Apologies if I have just done a huge post for something that is wide of the mark...