I had something similar, Ebbie - my mother assumed in her last years that I was her younger sister,and kept asking after "mother". My aunt had died some years previously: my grandmother died before I was born.

I worked out in the end that she had completely elided the 60 years of her married life and reverted to somewhere in the middle of WW2 - this was I think, to explain to herself why she was living in a home with other women in a strange place. She thought she was a refugee of some sort.

Paws