Altering notification BCC with gform_pre_submission_filter not working

We are following this guideline: http://www.gravityhelp.com/documentation/page/Gform_pre_submission_filter

Basically I have a custom function to determine the email recipients for the Admin notification, which I put into the $form['notification']['bcc'] field... however, it appears that this no longer has any effect.

I'm assuming this is due to the change in how notifications are handled, starting in the latest Gravity Forms update. I took a look at the form object, and now I see this, which leads me to believe I need to edit the BCC field under the specific Admin notification array, but how do I do this reliably? Is that array key 51c1ce591e9d4 always going to be the same?

[notifications] => Array
        (
            [51c1ce591e9d4] => Array
                (
                    [id] => 51c1ce591e9d4
                    [to] => trevor@designbygraphite.com
                    [name] => Admin Notification
                    [event] => form_submission
                    [toType] => email
                    [subject] => Bid Request
                    [message] => {all_fields}
                    [bcc] =>
                    [from] => trevor@designbygraphite.com
                    [fromName] => TREVOR
                    [replyTo] =>
                    [routing] =>
                    [conditionalLogic] =>
                    [disableAutoformat] =>
                )

            [51c46e55a4657] => Array
                (
                    [id] => 51c46e55a4657
                    [name] => Client Notification
                    [event] => form_submission
                    [to] => 4
                    [toType] => field
                    [bcc] =>
                    [subject] => Your Bid Request
                    [message] => Thank you for submitting your bid request.

{all_fields}
                    [from] => trevor@designbygraphite.com
                    [fromName] => TREVOR
                    [replyTo] =>
                    [routing] =>
                    [conditionalLogic] =>
                    [disableAutoformat] =>
                )

        )

Jose: I basically just modified the array like this:

$form['notifications']['51c1ce591e9d4']['bcc'] = "email@example.com,email2@example.com";

To find that unique indentifier, just edit the notification in the backend: you can see it in the URL...