In case I messed something up, here’s the code I used on my single-company.php to generate the Read More link:
<?php
$company_ID = $post->ID; //get the id of the current company
$archive = get_post_type_archive_link('post').'?company='.$company_ID;
?>
and here’s the code on my archive.php page:
<?php get_header(); ?>
<?php // if is a link to Read More from company single related post
if(isset($_GET['company'])){ ?>
Show all related posts from the company's singular page.
<?php } else { ?>
<?php while ( have_posts() ) : the_post(); // The Loop ?>
<?php get_template_part( 'content','excerpt' ); ?>
<?php endwhile; ?>
<?php } ?>
<?php get_footer(); ?>
