DataObject and SiteTree or Page and custom CMS fields

Hi,

I would like to know how to best go about adding a relatively simple has_one relationship. I have a class extending DataObject, lets call it EditedAuthor. It has 2 simple Text data fields.
So, the code looks like this (at the moment):

<?php
class EditedAuthor extends DataObject {

    public static $db = array(
        'AuthorTitle' => 'Text',
        'AuthorCaption' => 'Text',
    );
    //...
    public function getCMSFields() {
        $fields = new FieldGroup();
        $fields->push(TextareaField::create('AuthorTitle', 'Author title', $this->AuthorTitle));
        $fields->push(TextareaField::create('AuthorCaption', 'Author caption', $this->AuthorCaption));
        return $fields;
    }
}
?>

I have a custom Page Type extending SiteTree (actually our custom Page which extends SiteTree).

In that I have a has_one relationship to EditedAuthor:

<?php
class InformationPage extends Page {

    // ...
    static $has_one = array(
        'Contributors' => 'EditedAuthor',
    );
    // ...
    public function getCMSFields() {
        // ...
        if (Permission::check('ADMIN')) {
            $authorsEditField = singleton('EditedAuthor')->getCMSFields();
            $fields->addFieldsToTab('Root.Main', $authorsEditField);
        }
    }
    // ...
}
?>

I couldn't find in the docs how to best do this. The requirement is that I have a DataObject that is not a page type but can be added to a page type because I may want to re-use it later.
Also, this EditedAuthor should be editable only by admins and then save to the DB.
What is the way to do this?