Final answer:
Merging cases in Dynamics 365 for Customer Service results in a master case containing all data from subordinate cases, while the subordinate cases get deactivated and no longer appear as active cases.
Step-by-step explanation:
When you use Dynamics 365 for Customer Service to merge cases, the outcome is that all data from the subordinate case(s), such as activities, attachments, and notes, will be transferred to the master case. The subordinate case(s) will then be deactivated, meaning they will no longer be active cases in the system. After the merge process, all related information can be found only within the master case, providing a single view of all pertinent details and communications associated with the customer's issue.