Somewhat similar to this question, but I don't just want to import. I have a bunch of This American Life podcasts that I downloaded using iTunes on another computer. I also have a This American Life podcast subscription on my current Mac with a bunch of podcasts downloaded.
I have already imported the old ones into iTunes. They show up as two separate podcasts, with the same name and metadata. The old ones have a "subscribe" link but I haven't clicked it, they're just sitting there. The new ones are subscribed and regularly downloading new episodes.
How can I merge the old ones into the newer, subscribed version of the podcast in iTunes?