wp_comment_at

<?php
// Comment At
function wp_comment_at ($comment_text, $comment = ''){
    if ($comment->comment_parent > 0) {
        $parrent        = $comment->comment_parent;
        $parrent_author = get_comment_author($parrent);
        $comment_text   = '@<a href="#comment-' . $parrent . '">' . $parrent_author .'</a> : '.$comment_text;
    }
    return $comment_text;
}
add_filter('comment_text', 'wp_comment_at', 20, 2);
?>