// The Member Decorator
class Account extends DataObjectDecorator {
public function extraStatics() {
   return array(
'has_many' => array(
'Customers' => 'Customer'
)
);
}
public function getCustomers(){
return $this->owner->Customers();
}
}

// the customer
class Customer extends DataObject {
static $db = array(
'Name' => 'Varchar',
'Address' => 'Text',
'Description' => 'Text'
);
static $has_one = array(
'Account' => 'Member'
);
function getCustomerFields_forPopup(){
return new FieldSet(
new TextField('Name'),
new TextareaField('Address'),
new TextareaField('Description')
);
}
}

// the Page Object with the Form
class CustomersPage extends Page {
}

class CustomersPage_Controller extends Page_Controller {

function init(){
parent::init();
}

function CustomersForm(){

$Manager = new DataObjectManager(
$this,
'Customers',
'Customer',
array('Name' => 'Name'),
'getCustomerFields_forPopup',
'AccountID='.Member::currentUserID()
);
$Manager->setParentClass('Member');

$fields = new FieldSet($Manager);

return new Form($this, 'CustomersForm', $fields, new FieldSet());
}
}

$Manager->setSourceID(Member::currentUserID());