Silkies are pretty docile birds. Is she smaller than the others, and was she in the same flock as the other birds? Could she have left a buddy behind at her previous home? My 2 silkies in my large mixed flock always stuck together. They would hang in the barn with the other 2 bantams. I would get her eating some moistened chicken feed and a little scrambled egg. You can try to feed a treat to all and include her, making sure that she gets an opportunity to have some. A few drops of Poultry NutriDrench or other electrolytes and vitamin product may give her a boost. Sugar water or Gatorade might as well. Is she having normal droppings? Watch for signs of coccidiosis. Be sure to show her where the food and water is. If she is afraid or being bullied, a wire dog crate with her own food and water might be a good place to get used to the place.