Well, this is not the way to go. You created a duplicate now that will be deleted.

A look into the FAQ would've been enough: "I want to add a missing season to a TV entry, but there is no "Add New Season" button!". If something is unclear always ask before.

Just change the status to Returning Series, add seasons/episodes and then change it back to ended. How long will it take you to transfer the data?

I didn't know how to go about it. It won't take long.

Next time you know it, thanks. Just tell me when you're finished so I can delete it.

Fixed it. Ready for deletion.