I mentioned this in a post yesterday,
It may be of relevance to you and I hope it helps, but am not absolutely sure it applies to children!!!!
If you live in the UK, all local Council Houses, have a welfare rights advisor. They are trained to help you fill in the PIP (old DLA) form. They know exactly what words and phrases to put as answers to the questions. They use a 275 page guide line booklet which they refer to to help with the completion of the forms. It is not just the answers to the questions but also the phrases and words that you use in your answer.
Another good source of information I found was
http://www.benefitsandwork.co.uk/
Without the help of the welfare rights officers I would never of got my PIP for both the care and the mobility component
Good luck with your claim
Regards
Mart