Help please

Hello, my mother has just received her letter to change from DLA to PIP & I’m hoping someone can give me some advice on how to fill in the forms.
She has Degenerative disc disease, fibromyalgia, Osteo arthritis , carpal tunnel syndrome, anxiety & depression just to name a few. She was on an indefinite award with DLA. What I wanted to ask is - as I am going to be writing the information on the form do I put the words coming from my mother, as in - I am unable to do this or that. Or would I put it from my point of view - my mother can no longer do this & that?
The form arrived late with the bank holiday & then got lost so I have to do all of this to sent it back by the 17th June! Her doctors have closed down so she is in a surgery that the doctors do not know her history as yet so I don’t know what to say to them for support. She has attended a pain clinic twice over the years but they signed her off as they were no longer able to help her. An OT visited her home in 2005 & it was adapted for her. They gave her a letter at the time to give to DLA so do I take a copy of that to send as supporting evidence for the adaptions she had done in her home even though it is from 2005? I have taken photos of the adaptions as I read someone did that to show as proof of them, but apart from that I just really don’t know where to start as everything I read on here confuses me to the point I don’t know how to word the struggles she suffers on a daily basis.
She has cut & scolded herself trying to prepare vegetables so I do all her cooking now. I help her with all aspects of her life including all the medication she takes, dressing & showering her. Do I just write all of that down from my point of view or do I put it as her saying it?
Any help will be much appreciated.