Copy parties are members that should have read only access to the ticket. You do not have to enter a Copy party when creating a ticket or ever if not needed.

Do not add a member as a Copy party that will be added as a Step. If you do this, the Step will not have the correct permissions and will need to updated in the Parties section of the ticket. It will need to be changed from Copy to Step in order for the step member to update their step.