[support] Install and configure modules only once for all websites running the same drupal install?

[dondi_2006]

Hello,

I have one single drupal installation for
several websites. Everything is in /var/www/html/drupal (apache on
Linux).

The drupal/sites  subfolder has one folder
per website, each with its own settings.php, files/, modules/.
each site has its separate mysql database.

The question is if it is possible in this context (which I
cannot change, doesn't depend from me) to install/configure a module once and have it work in every website using that drupal
installation.

If I understand itcorrectly, the answer is no, because I *could*
only install one file and link to it from each modules/ folder, but I'd still have to log in to each single site to enable the module, right? Or not?

TIA,
D.