Nesting the CTE doesn't work either:

SELECT *
FROM (
  SELECT *, ROW=ROW_NUMBER() OVER (
   PARTITION BY facility_identifier, stay_number, episode_sequence_number
   ORDER BY replica_valid_from_date DESC
  )
  FROM (
   SELECT *
   FROM [dbo].[EPISODE]
   WHERE (
   (? <= [replica_valid_to_date] AND [replica_valid_to_date] < ?)
   OR
   (? <= [replica_valid_from_date] AND [replica_valid_from_date] < ?)
   )
  ) x
) x
WHERE ROW=1

The error message says put the entire block of code in a variable - also doesn't work.