First or third person reference as appointee from PIP to DLA

Hi Rishi,
You are appointee, and you are writing because your son is unable. This would therefore require 3rd person . You can say 'My son can not do X because...' If you write as 'I can't do X' then this is misleading. DWP will think why is the person requiring an appointee if he can write the form himself...which could then lead to well hmmm maybe since he doesn't need an appointee, maybe he doesn't need PIP either!!!!
Everything in 3rd person ie my son/he
You can also write your own observations, eg 'I have to dress my son every morning because...' explain the help you actually give and why.
Since you are appointee you can sign the form as appointee, in your name. I suggest that you might want to include additional info (in the space provided or on separate sheet - with name /NI Number clearly marked on all pages) explain your son's illness/disability giving an overview - was this from birth or a subsequent accident etc - explain why you became appointee. You can also expand on what help etc you give your son in terms of PIP activities.
I hope this helps.
LL26