My heart is simply aching for your family and especially your sister. I just put my 5 yr old in bed, and I can't even imagine losing her. Just did a quick search and found this poem...don't know if it fits what your looking for, but thought I'd send it just in case. May God give you His peace that surpasses all earthly understanding and comfort each of you now and always!
The Cord
We are connected,
My child and I, by
An invisible cord
Not seen by the eye.
It's not like the cord
That connects us 'til birth
This cord can't been seen
By any on Earth.
This cord does it's work
Right from the start.
It binds us together
Attached to my heart.
I know that it's there
Though no one can see
The invisible cord
From my child to me.
The strength of this cord
Is hard to describe.
It can't be destroyed
It can't be denied.
It's stronger than any cord
Man could create
It withstands the test
Can hold any weight.
And though you are gone,
Though you're not here with me,
The cord is still there
But no one can see.
It pulls at my heart
I am bruised...I am sore,
But this cord is my lifeline
As never before.
I am thankful that God
Connects us this way
A mother and child
Death can't take it away!
Author Unknown