Laravel request validation by groups

Question

So, I have a Creators table with all informations related to the creator.
This table has some nullable columns that can be filled depending on what type of creator you are.
As an example one can be an "indipendent" creator or a "company" creator. In the second case the creator will have to fill in the columns related to his company. At the moment I am arranging it with something like this inside the Controller:

    public function isValid(Request $request)
    {
        $creator = //creator validation rules;
        $company = //company validation rules;
        $transfer = //another set of rules;
        if (!$request->indipendent)
            $creator = array_merge($creator, $company);
        $creator = array_merge($creator, $transfer);
        return $request->validate($creator);
    }

I want to however create a new CreatorRequest that validates the request.
The only method I could think of was to override the validate() function, but is there a way to do this by only utilizing the rules() function?
Ideally I would like to have the $creator $company and $transfer inside the rules and be able to choose which groups I want validated.
For example:

$request->validate(['creator', 'company']); //doesn't validate transfer

What is the best approach?