drupal 7: How do I add individual css elements to an existing module css drupal 7: How do I add individual css elements to an existing module css so that if later on when this module css is updated when the module is updated my individual css are not deleted?
You don't. You are supposed add your individual CSS files in your custom themes (possibly sub-themes of existing ones) or in your custom module.

In both cases, do it using stylesheets[all][] = your.css clausule in module's .info file or theme's .info file.