randyhoyt

This plugin provides a number of helpers functions to aid in the creation of subordinate relationships between two post types, one-to-many relationships in which posts of one type are children of another. (For example, a Job Listing might have a Company as a parent; a Meeting might have a Group.) With this plugin activated, developers can easily write code in their plugins and themes to register two post types related in this manner.
For an example on how to use the functions this plugin makes available, check out my Groups and Meetings plugin on Github:
<ul>
<li>https://github.com/randyhoyt/mythsoc-groups</li>
</ul>

Subordinate Post Type Helpers

This plugin provides a number of helpers functions to aid in the creation of subordinate relationships between two post types.

scribu

AyeCode

Stiofan

Alex Ciobica

This plugin allows you to create many-to-many relationships between posts of any type: post, page, custom etc. A few example use cases:
<ul>
<li>manually curated lists of related posts</li>
<li>post series</li>
<li>products connected to retailers</li>
<li>etc.</li>
</ul>
Additionally, you can create many-to-many relationships between posts and users. So, you could also implement:
<ul>
<li>favorite posts of users</li>
<li>multiple authors per post</li>
<li>etc.</li>
</ul>
<h4>Support & Maintenance</h4>
AyeCode Ltd have committed to security and maintenance updates due to this plugins requirement in our <a href="https://wpgeodirectory.com/downloads/list-manager/" rel="nofollow ugc">List Manager Extension.</a>
~~I, scribu, will not be offering support (either free or paid) for this plugin anymore.~~
If you want to help maintain the plugin, fork it <a href="https://github.com/scribu/wp-posts-to-posts" rel="nofollow ugc">on github</a> and open pull requests.
Links: <a href="http://github.com/scribu/wp-posts-to-posts/wiki" rel="nofollow ugc">Documentation</a> | <a href="http://scribu.net/wordpress/posts-to-posts" rel="nofollow ugc">Plugin News</a> | <a href="http://scribu.net" rel="nofollow ugc">Author’s Site</a>

Posts 2 Posts

It works great. The options are beautiful, thought for every need, for example change a label or show only "to" box.

Works great

I'm working with WordPress, after some updates or actions the plugin starts to work incorrectly. The code is completely unreadable and can not be changed, the author abandoned his creation.
You can use - https://wordpress.org/plugins/npc-neatekpostconnect/

Huge load, unreadable code, Alternative for that plugin

Efficient many-to-many connections between posts, pages, custom post types, users.

Subordinate Post Type Helpers vs Posts 2 Posts