List child categories, link to particular div

I’m developing a theme for a client and they have a LOT of child pages that all use the same template.

I’ve used this code

<?php
  			if($post->post_parent)
 				 $children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0");
  			else
  				$children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
  			if ($children) { ?>
  				<ul class="sub-menu">
  					<?php echo $children; ?>
  				</ul>
 		 <?php } ?>

what I want to be able to do is link all the child page links to a particular div within the template so the page isn’t jumping about all the time when a link is clicked

Any help would be greatly appreciated

Thanks in advance.