Attaching Posts with CMB2 for WordPress

Important Links:

CMB2 Attached Posts Field - https://github.com/WebDevStudios/cmb2-attached-posts

https://webdevstudios.com/2014/12/23/attaching-posts-with-cmb2-for-wordpress/

https://wordpress.org/plugins/posts-to-posts/

https://github.com/scribu/wp-posts-to-posts/wiki/Basic-usage