Help with advanced custom page navigation.

Hello.

I’m trying to fix a page list system in WordPress. I have searched everywhere and tried many codes found on different places and reading the WordPress codex…

Here’s the structure that I’d like to achieve:

“Projects” is the mainpage. On this mainpage I’d like to have it’s subpages listed like:
-> Project 1
-> Project 2
-> project 3 etc…

On every subpage listed above there will be more subpages related to them (let’s say we click on “Project 1”, I’d like to display these subpages):
-> Subpage 1 of project 1
-> Subpage 2 of project 1
-> Subpage 3 of project 1 etc…

Now let’s say I click on “Subpage 1” this page will be displayed BUT I’d also like to display the other subpages related to “project 1”. So if I click on “Subpage 1” I’d like to display “Subpage 2” and “Subapge 3”.

I really hope you understand what I’d like to achieve here.

Here’s the code I’m working on and trying trying to fix my issue. Or maybe I’m doing it all wrong?

<ul>
    <li id="parent-page">Projects</li>
    <?php

    $args123 = array(
    'title_li'			=> '',
    'child_of'			=> $post->post_parent,
    'sort_column'		=> post_date,
    'sort_order'		=> desc,
    'echo'				=> 0,
    'depth'				=> '1'
    );

    $args456 = array(
    'title_li'			=> '',
    'child_of'			=> $post->ID,
    'sort_column'		=> post_date,
    'sort_order'		=> desc,
    'echo'				=> 0,
    'depth'				=> '1'
    );

    if($post->post_parent)
    $pages22 = get_pages($args123);
    else
    $pages22 = get_pages($args345);
    $count = 0;

    foreach($pages22 as $page)
    {
    $content = $page->page_parent;

    $content = apply_filters('the_content', $content);
    ?>
    <li id="pages"><a href="<?php echo get_page_link($page->ID) ?>"><?php echo $page->post_title ?></a></li>
    <li class="sub-list"><?php echo get_post_meta($page->ID,'video',true); echo get_post_meta($page->ID,'text_vimeo',true); ?></li>
    <?php } ?>
    </ul>

The code above works like this now:

The mainpage “Projects” display ALL pages (even other mainpages).

Subpage “Project 1” display all other subpages (Project 2, Project 3..) and their respective subpages.

Subpage 1 of project 1 displays “correct” except that the page itself is also displayed.

How to go further from here?

Kind regards
Johan