list pages three separate navs

Hello, I’ve been using the code:
<?php wp_list_pages(‘title_li=&depth=1’); ?>
to list all my parent pages horizontally in header navigation in a site that is not live yet.

I’ve also been using this:

<?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 id=”subnav”>
<?php echo $children; ?>

to list all child pages (which also shows grandchild pages which I’d like to avoid).

What I would ideally like to do is have parent page list on all pages, child page list in a sub navigation of a ancestor page only and a third navigation (grandchild page) to appear in the sidebar navigation on child pages only.