{{{ Pikky~! }}} i can't believe the number of people who get upset that i have terminal conditions... (well, this week they are improved greatly, which gives me hope, but the attitudes remain.)
this culture deals with death only on TV , not at first hand. i think your sister is far more usual than not. leave her to her way, and let her deal when it's too late. i have had an aunt with ALZ take a long time to go, and her daughters were in total denial, demanding that she recognize them, etc. how sad.
she thought i was her baby sister,,, and i let her. we had some lovely conversations. but she kept asking me: what's wrong (with me)?? no one could help her to understand, it's the condition itself that robs one of understanding.
i admire you so much for your struggle to remain connected to your mom to the end. big hugs~!

and much love~
your friend~
Gus