For series that contain unaired episodes (typically, these are episodes that were produced, never aired, and subsequently released on DVD) — you may add them to the appropriate season they belong to, but they must be added without an air date. If they were later released for streaming by the original broadcaster then that date can be used. Otherwise they remain empty.

In the future, the DVD order will be able to contain episodes that don't exist in the aired order. When this happens, you will be able to add these unaired episodes to the DVD order, with the release date as the date the episode was released on DVD in its country of origin.