Custom taxonomy position in admin panel
It will definately not show in custom_1 because you probably must have defined it for custom_2.However, you can define a custom submenu with link same as that of the taxonomy in which the parent link is that of custom_2. Following is what i mean. add_submenu_page( ‘edit.php?post_type=custom_1’, ‘Page Title’, ‘Menu Title’, ‘add_users’,’edit-tags.php?taxonomy=custom_taxonomy’, ” );