WP Registration Integration to include FNAME + LNAME

My MailChimp Audience is edited to require Email Address, First Name, and Last Name.

I’ve also modified my account registration form in WP to require First Name and Last Name using a woocommerce hook.

Is there a way to modify the “Registration Form integration” in mailchimp-for-mp so that it will also send the FNAME and LNAME fields captured at registration, as part of the “checkbox” integration?

I thought this may be possible by changing the $data variable in the”class-registration-form.php” to an array, and storing the EMAIL, FNAME, and LNAME elements.

But, when doing so, the MailChimp API throws a response of ‘The resource submitted could not be validated. For field-specific details, see the ‘errors’ array.’

Any suggestions or workarounds?