The WP Discourse plugin lets you link an existing Discourse topic to a WordPress post. To do this, go to the post’s edit page on WordPress and select Link to Existing Topic from the Discourse meta box. In the Topic URL field, enter the URL of a topic from your forum. You can get the URL from your browser’s address bar, or from any of the topic’s share links. (Note: you need to be on at least version 1.6.5 of the plugin to be able to use the share link URLs.)
Click the WordPress Publish or Update button to link your post to Discourse.
When the topic has been linked, it will function in the same way as a topic that you have published from WordPress to Discourse. If you have selected the Use Discourse Comments option (found on the Commenting Settings tab) the topic’s comments will be displayed underneath the post.
Once a topic has been linked to Discourse, selecting the Update Discourse topic checkbox will cause the post’s content to overwrite the Discourse topic’s content. Checking this box opens a confirmation dialog that must be agreed to before the post is updated.
Linking the post to a different topic
If you ever wish to link the post to a different Discourse topic, select the Unlink Post from Discourse checkbox and then click the WordPress Update button. This will remove all Discourse metadata from the post. You can then link the post to a different topic.