Disabling iMessages from appearing on devices that share the same Apple ID account — For TELUS Business customers
How to stop iMessage sharing across multiple devices that use the same Apple ID
If multiple people are using the same Apple ID on different devices you may find:
The iMessage accounts on those devices are linked. Any messages sent or received through the Apple Messages app will be available on all devices using the same Apple ID.
To solve this, you need to disable the unwanted email addresses and phone numbers linked to iMessage on all devices that are using the same Apple ID.
How to disable unwanted email addresses and phone numbers