When you create a version, it is of the entire geodatabase and cannot be done on a feature class by feature class level. You can set version permissions to Public, Protected, or Private which enables users to view and/or edit feature classes within a version based upon feature class permissions.My suggestion would be to grant read only privileges on your irrigation and trees feature classes to user1 and user2 respectively.Now to avoid user1/user2 being able to post to DEFAULT, set DEFAULT to Protected. Only SDE can post changes to DEFAULT and not user1/user2. I would create a QAQC version off of DEFAULT (perhaps set to PUBLIC) for user1/user2 to post changes to. Then SDE can review those changes and post to DEFAULT as needed. Please see the following ArcUser article - Versioning 101 - for more information on versioning and versioning workflows.Regards,Robert LeClairEsri-Denver