In Google bookmarks, how to rename a tag to two new tags? I.e. for each of the bookmark tagged 'foo', I'd like 'foo' deleted for it and two new tags 'new1' and 'new2' added.
This is currently not possible in Google Bookmarks. The quickest method would be the following: At the bottom of the Google Bookmarks page you can click "manage labels" and than "rename" your existing tag. After you have done that, find your new tag on the very left. Click it to get a list of your bookmarks labeled with this tag and than manually add your second tag to every bookmark.