hi, if you want to use bookmarks like this you should consider tags instead of folders to organise them, since you can assign multiple tags to a single bookmark without much effort...

You can do a Copy & Paste in the Bookmarks Manager (Shift+Ctrl+B) to create a copy of a bookmark. You can drag a link or tab or globe/padlock (Site Identity Button) on to the combined bookmark's star or "Show your bookmarks" button to open the drop-down list and drop the bookmark in the position where you want it. You can also drag the "Site Identity Button" (globe/padlock) on the left hand end side of the location bar to a folder in the Bookmarks menu drop down list or to a folder in the Bookmarks sidebar (Ctrl+B) or onto the Bookmarks Toolbar.