How does the narrator's attitude change toward her dead sister in "The Leap"?

Are you referring to the baby that the narrator's mother
lost when she had her accident in the circus? Of course, the narrator never actually
knows this "sister," and the baby dies we are told when her mother is taken to hospital
and she hemorrrhaged, and she is kept in bed for a month and a half before giving birth
to the stillborn baby. Although the narrator interestingly says that she never thought
of this child as a sister, she still acknowledges that she used to go to where her dead
half-sister was buried just to sit:

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Sometimes I used to walk there just to sit. She
was a girl, but i rarely thought of her as a sister or even as a separate person really.
I suppose you could call it the egocentrism of a child, of all young children, but I
considered her a less finished version of
myself.

Clearly, the grave of
her dead sister is important to her, however, as the narrator imagines that "the statue
is growing more sharply etched, as if, instead of weathering itself into a porous mass,
it is hardening on the hillside with each snowfall, perfecting
itself.

The narrator feels therefore a strong attachment to
her sister, which seems to only grown and become more important as the years go by,
instead of just fading away as perhaps you might expect.