package Organization;

...

sub recruit {
  my $self = shift;
  my $new_hire = shift;
  $self->add_employee(Employee->wrap($new_hire));
  return $self;
}

package Employee;

sub wrap {
  my $class = shift;
  my $person = shift;

  $class->new->set_person($person);
}

sub set_person {
  my $self = shift;
  my $new_person = shift;
  $self->{person} = $new_person;
  return $self;
}

sub surname {
  my $self = shift;
  $self->person->surname;
}

sub employee_number {
  my $self = shift;
  $self->{employee_number};
}
...