$order->{delivered_amount} = sum map { $self->sum_relevant_items(order => $order, other => $_, by_order => 1) } @delivery_orders;
$order->{billed_amount} = sum map { $self->sum_relevant_items(order => $order, other => $_) } @invoices;
$order->{delivered_amount} = sum map { $self->sum_relevant_items(order => $order, other => $_, by_order => 1) } @delivery_orders;
$order->{billed_amount} = sum map { $self->sum_relevant_items(order => $order, other => $_) } @invoices;