designtopack/public/site/config/hooks/create-steps.php

<?php

return function($page) {  
  if ($page->template() != "project") return;

  $page->createChild([
    'slug' => 'client-brief',
    'template' => 'client-brief',
    'content' => [
      'title' => 'Brief client'
    ]
  ]);
  
  $page->createChild([
    'slug' => 'proposal',
    'template' => 'proposal',
    'content' => [
      'title' => 'Offre commerciale'
    ]
  ]);
  
  $page->createChild([
    'slug' => 'extended-brief',
    'template' => 'extended-brief',
    'content' => [
      'title' => 'Brief enrichi'
    ]
  ]);
  
  $page->createChild([
    'slug' => 'sample',
    'template' => 'sample',
    'content' => [
      'title' => 'Échantillon virtuel'
    ]
  ]);
};