[Filipe Deschamps]

Finally figure it out.

It’s the bb_create_nonce();

It’s like an MD5 hash, formed by “create-post_” + “topic_id”

for example:

<input type="hidden" name="_wpnonce" value="<?=bb_create_nonce('create-post_3');?>"

With this, you can create replies (posts) within the topic with id 3.

Best regards.