As a basic principle, it's important to know that one AWS account can only be linked to one Mobile Connect organization. This means that if you want to set up multiple account on Mobile Connect that are linked to different Amazon Connect environments, you'll need to use your separate (sub-)accounts in AWS. This is also indicated as a best practice in AWS.
For example:
These accounts need to be set-up separately via AWS marketplace and all have a separate configuration in our admin console.
The following limitations apply: