The short answer is yes you can.
class FieldsetParent extends Zend\Form\Fieldset
{
public function init() {
$this->add(array('name' => 'fieldA'));
$this->add(array('name' => 'fieldB'));
$this->add(array('name' => 'fieldC'));
}
}
class FieldsetFoo extends FieldsetParent
{
public function init() {
parent::init();
$this->add(array('name' => 'fieldD'));
$this->add(array('name' => 'fieldE'));
$this->add(array('name' => 'fieldF'));
$this->add(array('name' => 'fieldG'));
}
}
class FieldsetBar extends FieldsetParent
{
public function init() {
parent::init();
$this->add(array('name' => 'fieldP'));
$this->add(array('name' => 'fieldQ'));
$this->add(array('name' => 'fieldR'));
$this->add(array('name' => 'fieldS'));
}
}