ざっくりですが、こんなかんじかなと。

<?php
$parents = get_categories(array('parent' => 0, 'hide_empty' => false));
foreach ($parents as $parent){
  echo "■{$parent->name}<br />"; // 親カテゴリ
  $children = get_categories(array('parent' => $parent->term_id, 'hide_empty' => false));
  foreach($children as $child){
    echo "・{$child->name}<br />"; // 子カテゴリ
    $child_posts = get_posts(array('posts_per_page' => 2, 'category' => $child->term_id));
    foreach ($child_posts as $child_post) {
      echo $child_post->post_title;
    }
  }
}
?>

• この返信は5 ヶ月前に  halbot さんが編集しました。