Problem Definition

In some cases, JIRA Service Desk administrator does not want the customer to be able to add a participant.

Suggested Solution

Add an option to disable sharing feature under Customer Permission and remove the Share feature from the Customer Portal.

Workaround

Here are some of the workaround that will help reduce the impact

• Disable notification for “Organization added” event from Project Settings > Customer notifications

• Disable automatic sharing of request with organization unless the customer manually selects an org at https://<YourSite>.atlassian.net/jira/settings/products/jira-service-management-configuration 

• • Set "Should new requests automatically be shared with a customer's organization?" to "No, don't share email requests with the customer's organization. Requests sent from the portal will not be shared unless the customer selects otherwise" option.

• Make sure to set the customer share permissions as per your requirement