2 件の回答
The items that show up in the Activity History of a record are items that have that record as the Related To field. Since you can only have one record as the lookup for that field, you'd can only have them show up as a record in Activity History on one record or another one, not both.
That being said you could create another lookup field and have a separate related list (could call it Case Activity History). You'd have to create some automation though to link it if you don't want to manually set it every time though. This dictates the case needing to be related to the Opportunity.
