17 yr Autistic daughter just refused PIP

We are legal guardians to our 14 year old grandson who has high functioning ASD. As the time for a PIP assessment becomes ever closer we are becoming more anxious about the outcome for him and for us. He has been diagnosed since he was 4 years old and has a dedicated team of professionals (couldn't get any help until his violence put me in hospital with a serious back injury 5 years ago) who are trying to help him control his behaviour. He has a myriad of problems including anxiety, obssessive and damaging behaviour in the home, no appreciation of danger (starts fires, obsessed with electrical items, poor hygiene, stealing cash, bank cards and credit cards to the tune of hundreds of pounds if he gets hold of them, plaster picking, wallpaper stripping, carpet chewing, obsession with water and will attack us or run if he gets upset in public to name just a few. The thing is, he is highly intelligent and very high functioning indeed. He is educationally normal although he needs an additional needs school because of the social difficulties that he experiences. His language is fluent, if a trifle quirky, and he believes himself to be completely right about everything. I have great fears for what will happen if the way he manages is questioned in an interview. He is likely to talk himself out of the benefits that he so badly needs. For instance....when asked how do you manage in the bathroom, he will say of course he can but in fact we get smearing, urinating on the roller blind, flooding, blocked loo, he wont wash his hands or flush the chain and he is busy destroying the bathroom floor at present. His psychiatrist has said that she will leave the assessors in no doubt about the depth of his challenges despite outward appearances but I have read that little notice is taken of the advice of professionals in the field. We are in our 50s and desperately need the 4 hours respite that we get per week and although it is funded the cost of the activities, food while out for him and his carer is paid for out of his DLA at present. The rest goes on repairing his room constantly as he breaks everything, replacing his clothing and shoes which he picks and pulls at until they fall apart, socializing him  (he would sit in front of his driving game on the computer all the time given the chance), and towards the cost of looking after his PAWS dog. He is on the higher rate for care and lower rate for mobility because although he can manage familiar routes he has no understanding of danger and so cant go out alone. If we lose his benefit we also lose my Carers allowance ( the stress and strains of caring for him for 9 years have taken a heavy toll on my ability to work) and the bonus for having a disabled child attached to the tax credits. We will still have him to care for despite having thousands of pounds per year knocked off the budget. Where among the questions that he will be given is there anything that will explore the complex condition he has?

We are legal guardians to our 14 year old grandson who has high functioning ASD. As the time for a PIP assessment becomes ever closer we are becoming more anxious about the outcome for him and for us. He has been diagnosed since he was 4 years old and has a dedicated team of professionals (couldn't get any help until his violence put me in hospital with a serious back injury 5 years ago) who are trying to help him control his behaviour. He has a myriad of problems including anxiety, obssessive and damaging behaviour in the home, no appreciation of danger (starts fires, obsessed with electrical items, poor hygiene, stealing cash, bank cards and credit cards to the tune of hundreds of pounds if he gets hold of them, plaster picking, wallpaper stripping, carpet chewing, obsession with water and will attack us or run if he gets upset in public to name just a few. The thing is, he is highly intelligent and very high functioning indeed. He is educationally normal although he needs an additional needs school because of the social difficulties that he experiences. His language is fluent, if a trifle quirky, and he believes himself to be completely right about everything. I have great fears for what will happen if the way he manages is questioned in an interview. He is likely to talk himself out of the benefits that he so badly needs. For instance....when asked how do you manage in the bathroom, he will say of course he can but in fact we get smearing, urinating on the roller blind, flooding, blocked loo, he wont wash his hands or flush the chain and he is busy destroying the bathroom floor at present. His psychiatrist has said that she will leave the assessors in no doubt about the depth of his challenges despite outward appearances but I have read that little notice is taken of the advice of professionals in the field. We are in our 50s and desperately need the 4 hours respite that we get per week and although it is funded the cost of the activities, food while out for him and his carer is paid for out of his DLA at present. The rest goes on repairing his room constantly as he breaks everything, replacing his clothing and shoes which he picks and pulls at until they fall apart, socializing him  (he would sit in front of his driving game on the computer all the time given the chance), and towards the cost of looking after his PAWS dog. He is on the higher rate for care and lower rate for mobility because although he can manage familiar routes he has no understanding of danger and so cant go out alone. If we lose his benefit we also lose my Carers allowance ( the stress and strains of caring for him for 9 years have taken a heavy toll on my ability to work) and the bonus for having a disabled child attached to the tax credits. We will still have him to care for despite having thousands of pounds per year knocked off the budget. Where among the questions that he will be given is there anything that will explore the complex condition he has?