Migrated from ESA Support Group to Universal Credit LCWRA

Hello. I am my son's appointee and also Attorney for Property, Finance, Health and Welfare. UC have informed me that my son is to be referred for a Work Capability Assessment. My son has autism, moderate learning difficulties and a complex cluster of medical conditions. These are lifelong disabilities.
When my son accepted his current job with Sainsbury, he migrated from Employment and Support Allowance (Support Group) with the LCWRA element as he was and is deemed to have limited capability for work. He could not remain on ESA because the Sainsbury job was working for 16 hours a week and was just over the threshold for him remaining on ESA. Our son has a strong work ethic and has tried his best, with support from me and others, to be gainfully employed, albeit in a limited capacity.
In 2021/2022, he was referred by our GP for a neuropsychological assessment in order to get up to date information about cognitive skills, mood, attention, working memory, processing speed, visuospatial/perceptual, language and memory as well as assessing his executive function. The 13 page report concludes, among other things: “due to his complex neurodevelopmental history, his cognitive abilities have been demonstrated to be significantly lower than those of a similar age across attention, processing speed and specific executive functions such as planning and organising”.
Also his latest DLA letter states that his middle rate care and lower rate mobility is awarded from "12/10/2001 indefinitely".
I have asked UC whether it is absolutely necessary for my son to have to go through the process of describing yet again, how his complex needs affect him and I would also ask that, regarding an actual face to face assessment, what experience and, more important, understanding, the assessor might have of autism or, more specifically, my son's higher functioning autism and how his difficulties impact on his ability to manage his medical conditions. I will of course plough through your extensive guide and make preparation for a WCA as I doubt they will reconsider. Is there anything you can add to help. The company carrying out the assessment is is "Health Assessment Advisory Service" Thank you.

Thank you for reply. You say "based on the Prognosis Date completed by the assessor in their report, so his existing LCWRA award continues in payment until a new Decision is made.". What is a Prognosis Date and how would I know about it? My son has autism, moderate learning difficulties, a rare pituitary disease and Type 1 diabetes. These are lifelong conditions and for ESA our GP confirmed that he is not going to "get better" and is more likely to see his health deteriorate. I have kept a copy of the ESA responses and also in 2021/2022 he underwent an extensive neuropsychological assessment which I will of course submit as part of medical evidence. And will ask our GP to write a new letter. I have asked UC why they want him to have a WCA now as there has been no change in circumstances or in his contractual hours. I am sure you are familiar with people like my son who do not fit the system. My son's "status" in the system is more about him not having to participate in work related activity or increase his hours than it is about the money. Thank you for all that you do. One last thing, is the guide dated November 2022, the very latest for UC50 form? Many thanks.

if i can ask a question on this thread for Gary reguards prognosis date, my esa85 says "i advise work unlikely in 2 years"
can you explain what this means please in your vast experience.