bbPress.org

untested theoretical plugin

add_filter('post_text','first_reply',999);

function first_reply($text) {global $bb_post;

if (!is_bb_feed() && (int) $bb_post->post_position==1) {$text.="<a name='first-reply'></a>";}

return $text;

}

Then to get the first-reply link for any topic,

<?php echo "<a href='".get_topic_link()."#first-reply'>replies</a>"; ?>