Importing images into a new Session/Capture Folder

I am a new user and shot some images tethered using a catalogue. Realising it is better to use a session for this purpose I have made a new session and imported the previous raw files into the Capture folder. However I can't see the images in the browser despite them being there when I look directly inside the folder. I am tempted to dump the images and start all over again. But wondered if it was possible to import in this way?