Thanks Federico; that explains things!
You cannot modify the SQL behind a Table or View that is added from the Database Expert and moreover what you're called a Command Object is NOT really what you think it is!
To be able to 'modify', you first need to add a Command Object via the "Add Command" option. This option should be available under the Database Connection name in the Database Expert.
Using this option you can add a SQL Query and report against it. The option to "Edit" the command in the Database Expert is available for such objects only.
Hope this helps!
-Abhilash