How to ignore apparent subpages

I am rewriting a WordPress site and plan to turn part of it into an angular app.

The site has a bunch of sub-pages of the form /recommendations/xxxxx. I need all URLs to remain accessible for SEO purposes, I will keep the /recommendations parent page but will do the sub-routing using Angular. but want all of the sub-pages to lead to the parent page BUT keep the sub-page routing in the URL for Angular to process.

I think I need to use add_rewrite_rule but have got stuck, and the following does not work. I need wordpress to show the recommendations page even if there is an extra url-part subsequently.

function recommendations_rewrite() {
      add_rewrite_rule('^recommendations\/(.*)\/?', 'recommendations/', 'top');
    }
    add_action('init', 'recommendations_rewrite');