The following fields are populated on Child Cases as the result of a merge, and can be used in the evaluation criteria for your automation.
- Status: The Merged Case Status you've defined on the Case Merge Premium setup wizard (usually, "Closed as Duplicate").
- Parent Case: Case Number of the Master Case chosen for the merge.
- Merged By: User who performed the merge.
- Merged Date/Time: Date/Time the merge occurred.
In order perform updates to the Parent Case, you will need to use Process Builder. For an example, see the following knowledge article