The menu and the "article sharing" are two differents things.
When you create a menu, you defined the "menu type" and can select different extension.
The "Article Sharing for JMS" is one of the menu type.
If the menu item appears in the master, this is probably because you defined the menu item in the master and not in the slave.
The "Article Sharing for JMS" just allows you to read articles comaing from other websites but do not share the menu item definition.
If you want to get menu item from another website, see the "Multisites Menu Items" product.
www.jms2win.com/en/joomla-multisite?page...36&category_id=1