My team inherited a Drupal 7 multi-site installation that was originally built with a custom installation profile and Drush make. I have all these sites running correctly in our environment now and want to bring an additional Drupal 7 standalone instance we support under this new multi-site configuration. I copied the database and created a corresponding subdirectory in the sites tree along with the proper edits to the sites.php file. The site does appear correctly when tested in a browser but the modules visible to the other instances are not seen by this site. Those modules are located under the profiles tree. I don't expect to need to use the install profile again and am inclined to copy the profiles/myprofile/modules directory contents to sites/all/modules to address this situation but am concerned about potential database dependencies. What is the best way to clean this up and have all multi-site instances aware of the same common modules?
variable_set('install_profile', 'name_of_custom_install_profile'); drupal_flush_all_caches();
from somewhere in the new site.
That'll trick your new site into thinking it was installed with the custom profile, and it should start checking that folder for contrib modules.