Ds is 3 and has severe speech delay - to the untrained ear most of what he says is very hard to understand. He is tall and looks 4 which is hard too. Dd is 6 and recently children have been making comments about ds - I can see her struggling to defend her brother from jibes but doesn't know quite what to say- she finds it hard to understand why he can't talk the way other kids do. I find it hard explaining in a way that children would understand...any advice