Karrde

Includes a file’s contents in the widget. Quick and dirty, all this does is use the PHP include function to include the specified file in the widget. There is NO checking done whatsoever on the file, so use it at your own risk. I wrote this because I couldn’t find a widget to do this ? plugins exist for using include in posts and pages, but not in widgets.

Include Widget

Includes a file's contents in the widget.

Mindvalley

This shortcode will allow you to include the content from any posts or pages.
Shortcode usage:
<ul>
<li>[mv_include id=’4′] (best for performance)</li>
<li>[mv_include slug=’the-post-slug’]</li>
<li>[mv_include path=’http://www.example.com/parent-page/sub-page/’]</li>
<li>[mv_include path=’parent-page/sub-page’]</li>
</ul>
The plugin also create a special post type that can be used for content that are for inclusion only.

Mindvalley Include Post Content

Creates shortcode [mv_include] to include content from another post/page.

Include Widget vs Mindvalley Include Post Content