CREATE TABLE table_54746 ("Father" CLOB, "Birth" CLOB, "Marriage" CLOB, "Became Queen" CLOB, "Ceased to be Queen" CLOB, "Death" CLOB, "Spouse" CLOB)

Leopold VI, Duke of Austria is the father-in-law of which person?
SELECT "Spouse" FROM table_54746 WHERE "Father" = 'leopold vi, duke of austria'
SELECT "Spouse" FROM "table_54746" WHERE "Father" = 'leopold vi, duke of austria'