[WordPress] Pagination for a parent page and their child pages.

paginate-parent-children.php

<?php
/**
 * Pagination for a parent page and their child pages.
 * Use as gp130428_link_pages() in your template file. 
 * Optionally limit to a particular parent page by passing its ID (i.e. 123) to the function: gp130428_link_pages( 123 )
 *
 */
function gp130428_paginate_parent_children( $parent = null ) {
	global $post;
    
	$child  = $post->ID;
	$parent = ( null !== $parent ) ? $parent : $post->post_parent;
	
	$children = get_pages( array(
				'sort_column' => 'menu_order',
				'sort_order'  => 'ASC',
				'child_of'	  => $parent
				) );
	
	$pages = array( $parent );
	foreach( $children as $page )
		$pages[] += $page->ID;
	
	if( ! in_array( $child, $pages ) && ! is_page( $parent ) )
		return;
	
	$current = array_search( $child, $pages );
		
	$prev = $pages[$current-1];
	$next = $pages[$current+1];

	?>
	<nav id="nav-single" class="clearfix">
	<?php 
		if ( empty( $prev ) && ! is_page( $parent ) ) : 
	?>
	<div class="previous"><a href="<?php echo get_permalink( $parent ); ?>" title="<?php echo esc_attr( get_the_title( $parent ) ) ?>"><?php echo get_the_title( $parent ) ?></a></div>
	<?php 
		elseif ( ! empty( $prev ) ) : 
	?>
	<div class="previous"><a href="<?php echo get_permalink( $prev ); ?>" title="<?php echo esc_attr( get_the_title( $prev ) ) ?>"><?php echo get_the_title( $prev ) ?></a></div>
	<?php 
		endif;
		if( ! empty( $next ) ) : 
	?>
	<div class="next"><a href="<?php echo get_permalink( $next ); ?>" title="<?php echo esc_attr( get_the_title( $next ) ) ?>"><?php echo get_the_title( $next ) ?></a></div>
	<?php 
		endif; 
	?>
	</nav>
<?php }

The gp130428_paginate_parent_children( 123 ) also includes the parent in the navigation, is there a way to exclude it?