How do I transfer stock between two Loaded companies?

For stock items: set both sites up as suppliers of each other, raise a credit note on the sending site and a matching purchase order on the receiving site, and use Stock Share so items and recipes don't need to be duplicated. For recipes: the receiving site sets the recipe up as a stock item purchased from the sending site, and the sending site processes it as a POS "sale" when it goes out, which handles the accounting without needing a credit note.