To modify the Envato Castle’s Plugin filters, You need to create the following directories and a PHP file inside your active theme

ACTIVE_THEME > oxibug > envato-castle > dev-factory.php

The file dev-factory.php will be included once it found from the plugin side, There’s no additional step to do from your side.

Now Just add the filters you need.

add_filter( 'FILTER_ID', 'FUNCTION_NAME' );

function FUNCTION_NAME( $builtin_array ) {

    return array_merge( $NEW_ARRAY, $builtin_array );

}