[MarkFL]

To add to the signature of the first post in a thread, you could create a plugin hooked at "postbit_display_complete" with the plugin PHP code:

PHP Code:

if ($post['postid'] == $thread['firstpostid'])
{
    $add = '<br /><br /><div style="color:green">This is added text</div>';
    $post['signature'] .= $add;
} 


Edit the content of the $add string to contain the HTML you want to add.