how to create pages and at the same time creating her children?

I try using populate defaults

 public function populateDefaults(){
            parent::populateDefaults();

            $p = new Page();
            $p->Title = 'TitlePage';
            $p->MenuTitle = 'MenuTitle';
            $p->URLSegment = $p->Title;
            $p->Content = '';
            $p->Status = 'Published';
            $p->write();
            $p->doRestoreToStage();
            $p->publish('Stage', 'Live');
            $p->flushCache();
    }

Any idea to create this structure?

A child is set by populating the ParentID with the ID of the parent

$parent = new Page();
$parent->Title = 'TitlePage';
$parent->MenuTitle = 'MenuTitle';
$parent->URLSegment = $parent->Title;
$parent->write();
$parent->publish('Stage', 'Live');

$child = new Page();
$child->Title = 'Child TitlePage';
$child->ParentID = $parent->ID;
$child->MenuTitle = 'Child MenuTitle';
$child->URLSegment = $child->Title;
$child->write();
$child->publish('Stage', 'Live');

i try but didn't work...

When create the page in CMS no child is created

using this code and work fine :)

  public function populateDefaults(){
            parent::populateDefaults();
            
            $this->write();
            $this->publish('Stage', 'Stage'); 
            
            $child = new Page();
            $child->Title = 'Child TitlePage';
            $child->ParentID = $this->ID;
            $child->MenuTitle = 'Child MenuTitle';
            $child->URLSegment = $child->Title;
            $child->write();
            $child->publish('Stage', 'Stage');
    }