How to use tables that are claimed by other modules in drupal?
You can expose information from other modules/"orphan" database tables from your own module by using hook_views_data in case nobody is exposing that table to views then you would "claim" it with all the consequences. If the table is already exposed to views but you want ton enhance the integration, you can use then hook_views_data_alter for adding fields, altering filters, etc.

You can find an example of how to implement a hook_views_data in the views documentation.