I was looking to migrate two Drupal sites. I think it is a multi-site setup, but I am not absolutely sure about that. The two sites have their own databases but the second site is sharing the first site's database as well. Again, I am not exactly sure how it is all set up, and that is why I need help.

The first site collects leads. It has a form which the user fills out. Then the data is saved on the current site. This is done using a custom Module's form.

The second site tracks the leads. This site is referencing its own database as well as the database of the main site, hence it is sharing the leads table from the first site's database.

I need help migrating these two sites to a new server and to keep the multisite setup in tact so the two sites still communicate with each other at the end.

So, I was looking for some help in understanding multi-site setups. I am a Drupal developer myself, but have no experience doing multi sites.

Thanks.