Custom content in clientareaproductdetails.tpl

[TK Greenwebspace.com]

Hello,

I used to display some custom content in the clientareaproductdetails.tpl using an include statement like:

include file="$template/customcontent.tpl"

Since the upgrade to WHMCS 8.1 this template uses the variable $tplOverviewTabOutput to display content:

{if $tplOverviewTabOutput}
  {$tplOverviewTabOutput}
{else}

How can I add custom content to this variable or what would be the best approach to solve my problem?

Thanks!