Code-Snippets-Functions/Execute a function on a child site/WooCommerce/add-or-remove-product-from-cart-if-another-product-is-added-or-remove.txt

add_action('woocommerce_before_calculate_totals', 'action_before_cart_calculate_totals');
function action_before_cart_calculate_totals( $cart ) {
    if ((is_admin() && !defined('DOING_AJAX')))
        return;

    $targeted_product_id = 67; // Define the targeted product ID
    $linked_product_id   = 15; // Define the linked product ID that should be added (complementary)
    $linked_item_key = $targeted_found = false; // Initialized variables

    // Check cart items
    foreach ( $cart->get_cart() as $item_key => $item ) {
        // Check if our targeted product is in cart
        if ( $item['product_id'] == $targeted_product_id ) {
            $targeted_found = true;
        } 
        // Check if the complementary product is in cart
        elseif ( $item['product_id'] == $linked_product_id ) {
            $linked_item_key = $item_key;
        }
    }

    if ( $targeted_found && ! $linked_item_key ) {
        $cart->add_to_cart( $linked_product_id ); // Add to cart the complementary product
    } elseif ( ! $targeted_found && $linked_item_key ) {
        $cart->remove_cart_item($linked_item_key); // Remove from cart the complementary product
    }
}