CompositeForm::getInternalForms

protected function getInternalForms();

public function load($data, $formName = null)
{
	$success = parent::load($data, $formName);

	$parentData = $this->getBaseFormData($data, $formName);
	foreach ($this->nestedForms as $name => $form)
	{
		if (is_array($form))
		{
			$success = parent::loadMultiple($form, $parentData, $formName === null ? null : $name) || $success;
		}
		else
		{
			/** @var BaseForm $form */
			$success = $form->load($parentData, $formName !== '' ? null : $name) || $success;
		}
	}
	return $success;
}