Hi,
1. If you want to display "the products related to the products already in the cart" on the checkout, there is a plugin available on our marketplace for that:
www.hikashop.com/marketplace/product/142-checkout-related.html
2. You'll have to edit the files "show" and "show_default" of the "product" view via the menu Display>Views in order to change that.
The related products are displayed by the code:
<div class="hikashop_submodules" id="hikashop_submodules" style="clear:both">
<?php
if(!empty ($this->modules) && is_array($this->modules)) {
jimport('joomla.application.module.helper');
foreach($this->modules as $module) {
echo JModuleHelper::renderModule($module);
}
}
?>
</div>
in the show view file. You can move that in the show_default view file based on where you want it.