////checkbox ellenorzes
add_filter( 'woocommerce_add_cart_item_data', 'bbloomer_store_gift', 10, 2 );
function bbloomer_store_gift( $cart_item, $product_id ) {
      $free_product_id = 8692;
      $quantity = 1;

      if( isset( $_POST['is-gift'] ) && $_POST['is-gift'] == "igen" && $product_id != $free_product_id ) {
          WC()->cart->add_to_cart( $free_product_id, $quantity );
      }
return $cart_item;
}