Generally we need to show one or more fields from a model that is related to another model used in CGridView.
For our case we will use two related models, which explain how to use model "A" fields in a CGridView that used model "B".
You have that, when a product is on development they can change its API anytime. This change is quite important though, its related on how to set the events of your form, for example, the useful beforeSubmit.
In a nutshell, the task at hand is to mark (or render) a model attribute in the typical "_form.php" view file with the 'required' red asterisk while this attribute is not marked as required in the model's rule() method.
If you're interested only in the solution, jump ahead to the 'solution' section below.