The plugins use 2 custom tables to store relations datas : https://github.com/scribu/wp-posts-to-posts/wiki/Data-organization Then if the plugin has not foreseen a export functionality, you have to retrieve the tables.
Export Custom Report as CSV
How can i customize the export personal data file?
Transfer only original images to new site
This is a notoriously difficult thing to solve in WordPress because of how the database is constructed. I have since long given up on being able to merge dev -> staging -> prod. Instead, I track any and all changes I make to the database in my dev environment, manually apply those to the production … Read more
How to retrieve current wordpress profile page URL?
There are lots of ways to get all IDs. Assuming you do want all posts – which include Posts, Pages, Media, Menu Items, custom post types, etc.: phpMyAdmin: Run a SQL query: SELECT ID FROM wp_posts then export the results to whatever file type you prefer.
403 export error when exporting pages from multisite subfolder site
WordPress does not import all pages and post
How do I migrate blog post images from one domain to a new one?