by Micah Wood on WordPress.org
The mPress Menu Wormhole plugin allows you to easily add a menu as a submenu to another menu.
Let’s say you have a sidebar menu where you list a special collection of important pages on your site. Now let’s say you want those same items to appear in a submenu off of your main header navigation. Now you have to manage the same collection of pages in two places. The mPress Menu Wormhole plugin makes it easy to maintain a single menu and have the changes you make to the sidebar menu automatically take place in the header menu as well.
Using this plugin is simple:
IMPORTANT NOTE: Please don’t direct a wormhole into itself… it creates a black hole. In other words, don’t add a navigation menu to itself. It creates an infinite loop that will crash the front end of your site. No worries though, it is easily undone. I do it just for fun sometimes.