Any article that you create or import into a folio in the Folio Builder panel appears in the folio. In addition, you can use two other methods to add articles to a folio.
In the Folio Builder panel, select the folio, and choose Share from the panel menu. Anyone with whom you share the folio can add articles to the folio. You can then use Copy To to copy articles from the shared folio to another folio, even if it's using a different account. See Share folios.
In the Folio Builder panel, select the article, and choose Copy To from the panel menu. Then copy the article to a different folio. All the metadata is transferred. You can edit and update the source files for a copied article as you can with an article you create. You can also copy an article using the Folio Producer Editor. See Copy an article to another folio.
If you need to transfer a folio from one account to another, use the Copy command in Folio Producer. See the "Copy folios" section in Creating folios.