Child Theme header1.php file not overwriting parent theme's header1.php file

Question

I am trying to add a custom header navigation to a WordPress site using a child theme (I'm using the Alphabet theme). I determined that I am using the header1.php file according to the styling inside and the selection I made in the admin view. I copied the header1.php file from the parent theme to the child theme and added in a new div block. However, the new div is not showing up.

I have registered my new menu in the WP admin successfully and have created links for it, the CSS in the child theme style.css file is being loaded when I check the source tab in Google Chrome's dev tools, and I have activated the child theme in the admin. I also made sure to replicate the includes -> header_layout directories inside my child theme.

I'm not sure what I'm missing? I don't want to add the new navigation into the parent theme because it will be overridden whenever the theme is updated and that's a major inconvenience. Is there another way I could create the custom navigation perhaps?

Edit: At the bottom of the header.php file, there is this block of code that grabs the appropriate header content depending on what the user selects in the admin:

<div class="header">
      <div class="inner_header">
          <!-- Start Header Position -->
          <?php if(alphabet_get_option('header_position') == 'header1') { include ( get_template_directory() . '/includes/header_layout/header1.php'); } ?>
          <?php if(alphabet_get_option('header_position') == 'header2') { include ( get_template_directory() . '/includes/header_layout/header2.php'); } ?>
          <?php if(alphabet_get_option('header_position') == 'header3') { include ( get_template_directory() . '/includes/header_layout/header3.php'); } ?>
          <?php if(alphabet_get_option('header_position') == 'header4') { include ( get_template_directory() . '/includes/header_layout/header4.php'); } ?>
          <?php if(alphabet_get_option('header_position') == 'header5') { include ( get_template_directory() . '/includes/header_layout/header5.php'); } ?>
          <?php if(alphabet_get_option('header_position') == 'header6') { include ( get_template_directory() . '/includes/header_layout/header6.php'); } ?>
          <?php if(alphabet_get_option('header_position') == 'header7') { include ( get_template_directory() . '/includes/header_layout/header7.php'); } ?>
          <!-- End Header Position -->
      </div>
    </div> 

Answer 1

That edit explains it. Alphabet is poorly written. Its use of php's include rather than WordPress's own include functions like get_header and get_template_part is breaking the parent/child hierarchy. You could probably make a copy of the file header.php and change those includes, as long as the file calling in header.php does it correctly!

As long as alphabet_get_option returns just those valid values or something falsy this should fix it:

<div class="header">
  <div class="inner_header">
      <!-- Start Header Position -->
      <?php
      $header_layout = alphabet_get_option('header_position');
        if( $header_layout ) {
            get_template_part( 'includes/header_layout/' . $header_layout );
        }
      ?>
      <!-- End Header Position -->
  </div>
</div>