If I create a mate, then I can click "new folder" and it makes a folder under the Paper Clips logo, and if I create other mates I can put them in that folder as well.

But I've got a stack of existing mates, and I clicked Paper Clips to create new folder, and it created a folder placed above the Paper Clips, but it wont allow me to drag existing mates up into it.

How do I get a stack of existing mates