> This is a **Developer level** doc. If you are unfamiliar with code and resolving potential conflicts, select a [WooExpert or Developer](https://woocommerce.com/customizations/) for assistance. We are unable to provide support for customizations under our [Support Policy](http://www.woocommerce.com/support-policy/?).
Add code to your child theme’s functions.php file or via a plugin that allows custom functions to be added, such as the [Code snippets](https://wordpress.org/plugins/code-snippets/) plugin. Avoid adding custom code directly to your parent theme’s `functions.php` file as this will be wiped entirely when you update the theme.
Please note that it does not work for all themes because of the way they’re coded.
```php
if ( ! function_exists( 'YOUR_PREFIX_related_products_args' ) ) {
/**
* Change number of related products output.
*
*@param array $args The related products args.
*@return array The modified related products args.
*/
function YOUR_PREFIX_related_products_args( $args ) {