Getting Started with Case Collaboration
|Knowledge Article Number||000073346|
The case collaboration feature allows you to add up to 20 individuals from your org to a case with Salesforce Support to keep them up to date on the status of the case. These individuals are known as case collaborators.
Please note this feature applies to Salesforce Support Cases accessible via the Help & Training Site. At the moment this is not a feature that you can enable for you own Service Cloud support channels and it's just available for Salesforce Support Cases. Idea Exchange link: https://success.salesforce.com/ideaView?id=08730000000kkhXAAQ
Useful information when adding case collaborators to your case: