Not easy but i hope to give you some good starting points.
Learn about "Template override". It means you can change the HTML output of component without hacking Joomla core code.
Use what learned at 1. so you can put an anchor near every article in your blog layout. Hint: you will have to change file:
/templates/[your template]/html/com_content/category/blog_item.php
If it's not there, create it by copying
/components/com_content/views/category/tmpl/blog_item.php
Let's say the anchor you put near every article is something link
<a id="article_<?php echo $this->item->id" ?>" />
- Depending on how displaynews plugin (or module?) is coded, you can use what learned at point 1. or you will have to hack the plugin (or module?) code itself. You can change the readmore link from
index.php?option=com_content&view=article&id=XX
to
index.php?option=com_content&view=category&layout=blog&id=CC#article_XX
where CC is the CATEGORY id, while XX is the ARTICLE id