How to add multiple sites with different address sets under a single customer account?

Summary:

We are unable to load multiple sites with the same address but with different address sets under a single customer account using the simple & complex template for customer upload FBDI. Take note that the customer already exists, we are using the templates to update/add the sites. When attempted rather than adding a new site under the customer account, it created a new customer account with a new sit .

Expected results

All have the same address, country, site name, and purpose. only the address set should be different