Nested attributes issue

Hi everyone. I faced with such problem: My model Order accepts nested attributes for model Address. It belongs to Address model and has shipping and billing address. I use nested forms to update or create addresses and everything is fine but I need to make an ability to mark checkobox 'use billing address for shipping' to avoid user to fill shipping address form and just use the same data as billing. So i can't understand how to do that. I receive attributes with their proper ids from DB and I can't just tell 'If checkbox so shipping_attributes = biling_attributes'. Here's my controller

  def update     return redirect_to address_path if @order.update(order_params)     render :show   end

  private

  def init_order     @order = current_order   end

  def order_params     params.require(:order).permit(shipping_address_attributes: address_params,                                  billing_address_attributes: address_params)   end

  def address_params     %i(id first_name last_name street zip_code city phone country)   end

So I should write some condition in update action to perform this. But how to do it most clearly???