i've been thinking about you and your boy Lynette. He sounds such a strong character.
When you look at what he's actually DOING, it is quite amazing. He refuses his mum, dad, and his headteacher about going into school even though he's only 8. He refuses adults requests to go into a classroom and sits stubbornly quiet and not talking to them.
There is no-one who can tell him what to do. That's amazing, when he's only 8 years old. Most kids have a point where they'll crumble - someone is able to do something to make that happen, whether it's rewards/praise/scary shouting/whatever! Doesn't seem like your ds has this point, so far....As you say it's about the transition but it also HAS to be about control, surely...your boy is in a power struggle with the adults here?
Is it possible the school could allocate him a support worker who could be his 'transition' person; they could greet him on arrival at school and take him in, and help him with his lesson change overs?
i just think you need a meeting with the head to make sure he realises that it's the transition he has to help your ds with. He may not see it so clearly as you do.
it's even crossed my mind that you could keep him off until his attendance is below 70%, then you could get help from the EWO!
Another alternative is to simply do your best with it, get him in as much as possible, and ride out this period of time; hoping that he changes, develops and that not focussing on it any more than you have to, you remove the power struggle element of the situation?
just thoughts really. HTH?