Hi,
I think that as you already have a number of children with a diagnosis that it would be sensible to have your son assessed as well.
He sounds like he is echolalic and uses delayed echolalia alot. My son is also on the autistic spectrum and he is supported in a mixed mainstream/special ed school. My son also (since age 3) has been repeating TV and DVD dialogue alot of the time.
I think he does that because he likes it. For him it is like he can re-play a TV programme or DVD in his head. But he also does it if he is bored at school because he doesn't understand what he should be doing, or when he is stressed he will retreat into his own world and watch TV in his head.
By scripting (or echolalia), that shows he has learnt language in a different way, and that he does have a speech disorder that is associated with autism. That is why he doesn't have much spontaneous speech. He should really be seen and assessed by a Speech and Language Therapist that has experience of autistic spectrum disorders and speech disorders. There is alot that can be done to teach children these skills, and although they never become automatic, they can learn phrases to say that can help them in social situations. For example my son is learning how to use learnt scripts to initiate play, join in, hold a conversation etc.
I don't know what country you are in, but as any of your children with autism get older and want to have more independence, they may need help and support to do that. In the UK we have Social Services who would be involved. So I think it is useful to start this process so that Social Services can also become involved (or your equivalent) as they may have alot of teenage and adult services that would be useful to them.
But I am rather surprised from your post that school have never raised the question of autism?
hoping someone can answer my ? please so im putting back on top of list