In author.php I have two loops: the default *main loop* that gets all posts from that author, and another custom *WP_Query* called `$secondloop`. Both queries have `posts_per_page` set to **3**. Now I'd like to **paginate both query results**.

For this I've added an argument to `$secondloop = new WP_Query($args)`:

    "paged" => (get_query_var('paged')) ? get_query_var('paged') : 1;
(read: set this query's page to the same page as the *main query's*).

# THE PROBLEM: #
 
 - If the *main loop* gives me 5 posts and my `$secondloop` gives me 2, then calling **page 2** works no problemo. It shows me the remaining 2 posts from the *main loop* and none from my `$secondloop` (since it doesn't go inside `while ($secondloop->have_posts())`).
 
 - **BUT** if the *main loop* has 2 posts and `$secondloop` has 5, then calling **page 2** results in **404** :(
I obviously want `$secondloop`'s remaining 2 posts instead.

Changing anything inside the author.php template doesn't help, because it seems that no PHP code in there is executed any more, once WordPress detects that `max_num_pages` from the *main loop* is exceeded.

**How can I "override" that behaviour?**


----------

# EDIT: ATTEMPT 1 #

Milo pointed me to an answer that suggested to add this to my **functions.php**:

    function my_404_override() {
      global $wp_query;
      
      if (is_author()) {
        status_header( 200 );
        $wp_query->is_404 = false;
      }
    }
    add_filter('template_redirect', 'my_404_override');

But it still shows me a 404 error. If I remove the if clause, then it leads me to the index.php which is not reeeally what I intended. My guess is that 

 1. either this code gets executed before WordPress knows what template it's dealing with (trying to execute get_current_template(true) in there throws an "Undefined function" error) 
 2. OR because `$wp_query->is_404` is **true** by the time this code is run, it doesn't attempt to load the author.php template.

Pasting the code directly to the template didn't work either, even if it's just these three lines pasted before `get_header();`:

    global $wp_query;
    status_header( 200 );
    $wp_query->is_404 = false;


I could now:

 1. figure out how to make this above attempt work, specifying a working if clause (because I don't want to redirect 404s *everywhere* and especially not to the index every time..). **Is that possible?** Especially, how can I remain inside my author.php template even if `$wp_query->is_404` is true?
 2. make 2 split paginations for both my main query and my `$secondloop` query and then altering my pagination function
 3. fiddle with AJAX (and the WP REST API, I assume?), which is not what I intended to do for a quick fix so I'd rather avoid it if the aforementioned solutions are quicker to implement.

----------

# THE CODE: #

**author.php** (just the useful bit)

    <?php if (have_posts()) { ?>
        <div class="row archive-grid">
            <?php while (have_posts()) : the_post();
                include(locate_template('parts/loop-archive-grid.php'));
                endwhile; ?>
        </div>
    <?php }

    $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
    $secondloop = new WP_Query(array(
        "post_type"      => "musikalbum",
        "posts_per_page" => 3,
        "author_name"    => get_query_var('author_name'),
        "paged"          => $paged
    ));

    if ($secondloop->have_posts()) { ?>
        <div class="row archive-grid">
            <?php while ($secondloop->have_posts()) : $secondloop->the_post();
                get_template_part( 'parts/loop', 'album-grid' );
            endwhile; ?>
        </div>
        <?php author_page_navi( $loop );
    } else {
        joints_page_navi();
    } ?>

Setting the `posts_per_page` for my *main query* in my **functions.php**

    function my_post_queries( $query ) {
      if (!is_admin() && $query->is_main_query()){
        if (is_author()){
          $query->set('posts_per_page', 3);
        } else {
          $query->set('posts_per_page', 9);
        }
      }
    }
    add_action( 'pre_get_posts', 'my_post_queries' );


And here are the **pagination functions** used from my JointsWP4 starter theme:

    <?php // This function was standard from my JointsWP4 starter theme...
    function joints_page_navi($before = '', $after = '') {
      global $wpdb, $wp_query;
      $request = $wp_query->request;
      $posts_per_page = intval(get_query_var('posts_per_page'));
      $paged = intval(get_query_var('paged'));
      $numposts = $wp_query->found_posts;
      $max_page = $wp_query->max_num_pages;
      //...except for this line, since author_page_navi uses the same logic:
      page_navi_logic( $posts_per_page, $paged, $numposts, $max_page );
    }

    // A "hacked" version of joints_page_navi() for my $secondloop to work (or not)
    function author_page_navi( $loop ) {
      global $wpdb, $wp_query;
      $request = $wp_query->request;
      $posts_per_page = max(intval($wp_query->posts_per_page), intval($loop->posts_per_page));
      $paged = intval(get_query_var("paged"));
      $numposts = max($wp_query->found_posts, $loop->found_posts);
      $max_page = max($wp_query->max_num_pages, $loop->max_num_pages);
      page_navi_logic( $posts_per_page, $paged, $numposts, $max_page );
    }

    function page_navi_logic( $posts_per_page, $paged, $numposts, $max_page ) {
      if ( $numposts <= $posts_per_page ) { return; }
      if(empty($paged) || $paged == 0) {
        $paged = 1;
      }
      $pages_to_show = 3;
      $pages_to_show_minus_1 = $pages_to_show-1;
      $half_page_start = floor($pages_to_show_minus_1/2);
      $half_page_end = ceil($pages_to_show_minus_1/2);
      $start_page = $paged - $half_page_start;
      if($start_page <= 0) {
        $start_page = 1;
      }
      $end_page = $paged + $half_page_end;
      if(($end_page - $start_page) != $pages_to_show_minus_1) {
        $end_page = $start_page + $pages_to_show_minus_1;
      }
      if($end_page > $max_page) {
        $start_page = $max_page - $pages_to_show_minus_1;
        $end_page = $max_page;
      }
      if($start_page <= 0) {
        $start_page = 1;
      }
      echo $before.'<nav class="push-down"><ul class="pagination">'."";
      if ($start_page >= 2 && $pages_to_show < $max_page) {
        $first_page_text = __( 'Erste...', 'jointswp' );
        echo '<li><a href="'.get_pagenum_link().'" title="'.$first_page_text.'">'.$first_page_text.'</a></li>';
      }
      echo '<li>';
      previous_posts_link( __('Back', 'jointswp') );
      echo '</li>';
      for($i = $start_page; $i  <= $end_page; $i++) {
        if($i == $paged) {
          echo '<li class="current"> '.$i.' </li>';
        } else {
          echo '<li><a href="'.get_pagenum_link($i).'">'.$i.'</a></li>';
        }
      }
      echo '<li>';
      next_posts_link( __('Forward', 'jointswp'), $max_page );
      echo '</li>';
      if ($end_page < $max_page) {
        $last_page_text = __( 'Last...', 'jointswp' );
        echo '<li><a href="'.get_pagenum_link($max_page).'" title="'.$last_page_text.'">'.$last_page_text.'</a></li>';
      }
      echo '</ul></nav>'.$after."";
    }