Prayers for God's peace to be on your Niece in this time of transition and for the Peace that passes all human understanding to be on your sister and her family.
My uncle, while dying of bone cancer, took me aside to explain his view of "being healed by faith". I'd asked "what if you're not healed?" for I was afraid it might rock his foundation of faith. Instead, his testament elevated my own faith immeasurably.
He looked at me, put his arm around my shoulders and quietly whispered in my ear, "David, even Death is God's perfect healing for there is NO Death for the true believer, just a new life!"
Amen.