i have module for delivery boys and i can assign the order to one of delivery boys and his name but i want to extend it to add delivery fees which is 10SAR 
i have created new product and named i Delivery Fee with barcode delivery12345 and the price and i was trying to extend the delivery boy assignment logic to add the product to the cart automatically when the delivery boy is chosen 

import { usePos } from "@point_of_sale/app/store/pos_hook";
import { ProductScreen } from "@point_of_sale/app/screens/product_screen/product_screen";
import { Component } from "@odoo/owl";
import { _t } from "@web/core/l10n/translation";
import { AlertDialog } from "@web/core/confirmation_dialog/confirmation_dialog";
import { SelectionPopup } from "@point_of_sale/app/utils/input_popups/selection_popup";
import { Dialog } from "@web/core/dialog/dialog";
import { ControlButtons } from "@point_of_sale/app/screens/product_screen/control_buttons/control_buttons";
import { patch } from "@web/core/utils/patch";
import { useService } from "@web/core/utils/hooks";

import { makeAwaitable } from "@point_of_sale/app/store/make_awaitable_dialog";


patch(ControlButtons.prototype, {
    setup() {
        this.dialog = useService("dialog");
        super.setup();
    },

    async confirmdelivery() {
        const order = this.pos.get_order();

        // Validate the order is not empty
        if (order.get_orderlines().length === 0) {
            this.dialog.add(AlertDialog, {
                title: _t("Empty Order"),
                body: _t("Please add at least one product to the order."),
            });
            return;
        }

        // Dynamically create the delivery fee product data
        const deliveryFeeProduct = {
            id: "delivery_fee_product", // Unique ID for virtual product
            display_name: "Delivery fee", // Product name
            list_price: 10, // Product price
            taxes_id: [], // No tax
            to_weight: false, // Not a weighted product
            uom_id: [1, "Units"], // Unit of measure
        };

        // Create a new order line with the delivery fee product
        const deliveryLine = new this.pos.models.Orderline(
            {
                product_id: deliveryFeeProduct,
                price_unit: deliveryFeeProduct.list_price,
                quantity: 1,
                taxes_id: deliveryFeeProduct.taxes_id,
            },
            { pos: this.pos, order: order }
        );

        // Add the order line to the current order
        order.orderlines.add(deliveryLine);
        console.log("Delivery Fee product added successfully.");

        // Show delivery boy selection popup
        const deliveryBoys = this.pos.pos_custom_delivery_boy || [];
        if (deliveryBoys.length === 0) {
            this.dialog.add(AlertDialog, {
                title: _t("No Delivery Boys"),
                body: _t("No delivery boys are configured. Please configure them first."),
            });
            return;
        }

        const selectionList = deliveryBoys.map((boy) => ({
            id: boy.id,
            label: boy.delivery_boy_name,
            isSelected: false,
        }));

        this.dialog.add(SelectionPopup, {
            title: _t("Select Delivery Boy"),
            list: selectionList,
            getPayload: async (value) => {
                console.log("Selected Delivery Boy:", value);
                order.set_delivery_boy(value.delivery_boy_name);
                order.update({ delivery_boy_id: value.id });
            },
        });
    },
});