As long as they are in your project you can still get them into your library, export them, 1 at a time, import it, during the import process make sure the box is checked to add to library, name the object, choose a folder to add it to, existing or create 1, i save mine to a folder called "mine", original eh. All this is done very simply during the import process.
There is also a "copy as new furniture" tool,never figured what that does.