Markus Echterhoff

If you have a multisite setup, you normally cannot have the same bbPress forums across all sites of the network. Now you can.
Install this plugin and activate it on the main site and for each subsite that should use the main site’s forums, or network-activate to enable on all sub sites.
If you want both main site and sub site forums displayed on the sub site, set a different root slug and topics slug in the forum settings. After that, both slugs will be known on the sub site and display their respective forums.
BUT! There is a reason why you cannot normally do this and that is because the code base is not really supportive of it. I have monkey patched my way to the goal and I’m doing some evil black magic like hooking ‘query’ and running regular expressions on the query. All of this is only ever done to your forum pages, so be cool, give it a try. If it works for you: great. If it doesn’t: deactivate, relax, look for a different solution (or patch mine).
Profile Note: Profiles are not merged! Favorites, topics started etc show main/sub site only. If you want your users to see all their subscriptions in one place, you’ll have to write some custom code and likely patch my code too.
BuddyPress Note: It does work with network enabled BuddyPress, but they don’t play together nicely because of the BuddyPress/bbPress integration stuff. I have monkey patched this to work. If you do not have BuddyPress installed in /members/ you’ll have to monkey patch my monkey patch, please see the code. And as for the profiles: Same thing as with bbPress profiles.

Multisite bbPress Slave

Make sub sites use the main site's bbPress forums

WP Zone

annaqq

BerryPress

This plugin enables the TinyMCE WYSIWYG editor for BBPress forum topics and replies and adds a button to the editor’s “Insert/edit image” dialog that allows forum users to upload images from their computer and insert them inline into their posts.
A <a href="https://berrypress.com/product/bbpress/image-upload-for-bbpress-pro/?utm_source=image-upload-for-bbpress&utm_medium=link&utm_campaign=wp-repo-upgrade-link" rel="nofollow ugc">pro version</a> with the following additional features is also available:
<ul>
<li>Change the directory where uploaded images are stored.</li>
<li>Limit which user roles are permitted to upload images.</li>
<li>Limit the number of uploaded images allowed per post.</li>
<li>Automatically downsize images to fit specified maximum dimensions.</li>
<li>Convert all uploaded images to the same image format, if desired.</li>
<li>Set PNG and JPEG compression levels so images take up less disk space.</li>
<li>Allow users to view enlarged images in a lightbox by clicking on them within the post.</li>
<li>View total image count and file size statistics.</li>
<li>Use <a href="https://aws.amazon.com/s3/" rel="nofollow ugc">Amazon S3™</a> to store and serve uploaded images in submitted forum posts (optional; requires <a href="https://berrypress.com/product/bbpress/image-upload-for-bbpress-pro/?utm_source=image-upload-for-bbpress&utm_medium=link&utm_campaign=wp-repo-upgrade-link" rel="nofollow ugc">add-on plugin</a> purchase).</li>
</ul>
Amazon Web Services, the “Powered by Amazon Web Services” logo, AWS, Amazon Simple Storage Service, and Amazon S3 are trademarks of Amazon.com, Inc. or its affiliates in the United States and/or other countries. Potent Plugins is not affiliated with Amazon.com, Inc. or Amazon Web Services.
If you like this plugin, please consider leaving a comment or review.
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<li><a href="https://wordpress.org/plugins/image-upload-for-bbpress/" rel="ugc">Inline Image Upload for BBPress</a> – enables the TinyMCE WYSIWYG editor for BBPress forum topics and replies and adds a button to the editor’s “Insert/edit image” dialog that allows forum users to upload images from their computer and insert them inline into their posts.</li>
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To view WP Zone’s premium WordPress plugins, visit our <a href="https://berrypress.com/shop/" rel="nofollow ugc">WordPress products catalog page</a>.

Inline Image Upload for BBPress

Upload inline images to BBPress forum topics and replies.

Multisite bbPress Slave vs Inline Image Upload for BBPress