13. The method of claim 1 , wherein the one or more candidate sibling queries are ranked for each child query.
13. The method of claim 1 , wherein the one or more candidate sibling queries are ranked for each child query. 15. The method of claim 13 , wherein the candidate sibling queries are ranked according to one or more of a number of parent queries shared by a given child query and each sibling, a quality of result statistic, or a click-through-rate for each candidate sibling query.