I just wanted to give you one of these.

There is a boy in prep with DS this year, and apparently he is nearly 6, and only started talking last year. I think he has other (different) issues than your DD though, his is a behavioural thing as well. But, he does play well with the other kids, even though he doesn't talk as well as the rest of them.

Maybe a play date is in order, DD1 will be going to Kindy next year, and we are taking her to get assessed for her behavioural stuff on the 27th.