I was quite sure my dad wanted to continue to give us his traditional £100 each at Christmas and £20 Birthday gifts this was just to myself, my husband and his two grandchildren, as he had been doing the same for well over 10 years since my mum had died. Even when his Dementia was getting worse he insisted on giving us money, so when he no longer understood about these events, I continued doing it for him, however, I did reduce the amount for myself and my husband.
I believe you have to act on behalf of the PWD and continue to honour what they would continue to do if they still had their full faculties, but it is also your responsibility as attorney to keep it within their means.