There are two ways a customer can be added to a new region.
Customer Process
Instruct your customer to log into their studio account. Under the 'My Info' section, the customer will select 'Allow Other Studios' under the 'Your profile is accessible to' section.
From this screen, the customer can select which region has access to their customer profile.
Studio Process
This process requires a CorpAdmin user to update.
If a CorpAdmin is logged in, they simply navigate to the region where the customer profile is currently accessible, edit their 'info' on the customer profile card, then edit the region access.