How could I just show orders from one Manufacturer on the Administration Orders Page?

             OrderCollection orders = OrderManager.SearchOrders(startDate, endDate, txtCustomerEmail.Text, orderStatus, paymentStatus, shippingStatus);
            Manufacturer manufactuer = ManufacturerManager.GetManufacturerByID(manufacturerID);
            int totalRecords = 0;

            ProductCollection products = ProductManager.GetAllProducts(0, manufacturerID, null,
                null, null, null, false, int.MaxValue, 0, null, out totalRecords);

            OrderCollection designerOrders = new OrderCollection();

            try
            {
                foreach (Order order in orders)
                {
                    bool includesManufacturer = false;
                    OrderProductVariantCollection orderProductVariants = order.OrderProductVariants;
                    foreach (OrderProductVariant orderProductVariant in orderProductVariants)
                    {
                        Product product = orderProductVariant.ProductVariant.Product;
                        if (products.Contains(product))
                        {
                            includesManufacturer = true;
                        }

                    }
                    if (includesManufacturer)
                        designerOrders.Add(order);
                }
            }
            catch
            {
            }

            return designerOrders;