designtopack/public/site/models/project.php

<?php

class ProjectPage extends Page {
  public function getSteps() {    
    $steps = [];

    foreach ($this->children() as $child) {
      $files = [];

      if ($child->stepName() == 'clientBrief') {
        foreach ($child->moodboard()->toFiles() as $file) {
          $files[] = getFileData($file);
        }
        foreach ($child->pdf()->toFiles() as $file) {
          $files[] = getFileData($file);
        }
      }

      $steps[] = [
        'text' => $child->title()->value(),
        'value' => $child->stepName()->value(),
        'index' => $child->stepIndex()->value(),
        'modified' => $child->modified('Y-MM-dd'),
        'uri' => $child->uri(),
        'files' => $files
      ];
    }

    usort($steps, function ($a, $b) {
      return $a['index'] <=> $b['index'];
    });

    return $steps;
  }
}