[TYPO3-mvc] where do I set "CONFIGURATION_CREATION_ALLOWED" to TRUE?

[Tim Schoch | GSTALTIG]

Hello Claus

The new property Mapper is enabled. 

If iirc the setup should be like this:
FLUID:
<f:form.textfield property="name" />
  <f:form.textfield property="datas.0.height" />
...
<f:form.textfield property="datas.N.height" />

DOMAIN MODEL (parent):

    /**
     * datas
     *
     * @var Tx_Extbase_Persistence_ObjectStorage<Tx_Myext_Domain_Model_Data>
     */
    protected $datas;


  /**
   * Adds a Data
   *
   * @param Tx_Myext_Domain_Model_Data $data
   * @return Tx_Myext_Domain_Model_HandHeight
   */
  public function addData(Tx_Myext_Domain_Model_Data $data) {}

  /**
   * Removes a Data
   *
   * @param Tx_Myext_Domain_Model_Data $dataToRemove The Data to be removed
   * @return Tx_Myext_Domain_Model_HandHeight
   */
  public function removeData(Tx_Myext_Domain_Model_Data $dataToRemove) {}

  /**
   * Returns the datas
   *
   * @return Tx_Extbase_Persistence_ObjectStorage<Tx_Myext_Domain_Model_Data> $datas
   */
  public function getDatas() {}

  /**
   * Sets the datas
   *
   * @param Tx_Extbase_Persistence_ObjectStorage<Tx_Myext_Domain_Model_Data> $datas
   * @return Tx_Myext_Domain_Model_HandHeight
   */
  public function setDatas(Tx_Extbase_Persistence_ObjectStorage $datas) {}

------

Do I have to allow the creation of Data objects explicitly? By the way: I know there is a tutorial on this, but i've googled "nested 
objects", "relations" and some other terms, but didn't find a thing (probaby I miss the right term) - does anybody know a link?

Thanks, Tim