Move a parent to where the children are

gistfile1.txt

	[MenuItem("Selection/Center on first child", false, 301)]
	static void Center() {
		
		Object[] objs = Selection.GetFiltered(typeof(GameObject), SelectionMode.Editable | SelectionMode.ExcludePrefab);


		foreach (GameObject go in objs){
			Transform child = go.transform.GetChild(0);
			Vector3 childPos = child.position;

			Vector3 childChange = childPos - go.transform.position;

			go.transform.position = child.position;
			foreach (Transform chld in go.transform) {
				chld.position -= childChange;
			}
		}
	}