Speaking from experience here !
DB's aged auntie was a wiley old girl, a very independent spinster lady who was quite switched on - till the bad stuff set in.
She had the sense, or advice, to set up an Enduring Power of Attourney. This was a document that named the people, in her case DB and his brother, who were to look after her affairs when she became incapacitated, in whatever manner - hospitalised, senile, in care etc - to be invoked when was deemed to be so by doctor and lawyer, whatever.
By setting it up some years before her decline she had the peace of mind that whatever happened she would be looked after and her finances would be properly administered for her benefit and all necessary decisions would be made by family and in her best interest.
The big advantage was that when it came time to take over her affairs the paperwork was already in place and invoked in a very short space of time. To set up a Power of Attourney takes months and in the meantime stuff can go to hell in a handbasket while you wait.
There's lots of info on the net. Only last week DB and I got our letters from the Registrar saying that our POA's were now official.
You do the necessary with a Lawyer and they notify the people you want to have the powers and obviously they have to give their agreement before it can go ahead.
This is nothing to with and has no effect on a Will. Obviously it is a big responsibility but one you will probably get anyway but it is so much easier with the proper documents in place.