How awful! Good for you that you are helping out. I'm so glad that child has someone to rely on. Perhaps her sister will come around once she sees how you are with her sister. This organization is DELIBERATELY ripping families apart by tearing away the natural affection families have. That is the whole reason they deny holidays - they are times of family bonding. They want people to worship them - not to have loyalty to family. They are despicable.
I wish you and your family all the best. Keep loving those kids. That will help them more than anything else. They desperately need adult attachments in a proper, caring and loving atmosphere.
Hadit