Modify friends list (add some Specific User role User)

functions.php

<?php
/**
 * Add some Specific User role User
 *
 * @param array $friend_ids
 * @param int $user_id
 * @return array
 */
function buc_add_friends_in_list( $friend_ids, $user_id ) {
	$users_role = array(
		0 => 'author',
		1 => 'administrator',
	);
	$args = array(
		'role__in' => $users_role,
		'fields'   => 'ID',
		'exclude'  => array( $user_id ),
		'orderby'  => 'display_name',
	);
	$new_friend_ids = get_users( $args );

	$friend_ids = array_merge( $friend_ids, $new_friend_ids );

	return $friend_ids;
}
add_filter( 'buc_modify_friends_list', 'buc_add_friends_in_list', 10, 2 );