function wpf_chainedquiz() {

    if ( ! function_exists( 'wp_fusion' ) ) { // Just in case they deactivate WPF, we don't want it to break
        return;
    }

    $email = sanitize_email( $_POST['chainedemail'] );

    $contact_id = wp_fusion()->crm->get_contact_id( $email );

    $contact_data = array(
        'user_email' => $email,
        'first_name' => 'fname', // Populate this with the first name
        'last_name'  => 'lname', // Populate this with the last name
    );

    if ( false === $contact_id ) {

        // Add new contact

        $contact_id = wp_fusion()->crm->add_contact( $contact_data );

    } else {

        // Update existing contact

        wp_fusion()->crm->update_contact( $contact_id, $contact_data );

    }

}

add_action( 'wp_ajax_nopriv_chainedquiz_ajax', 'wpf_chainedquiz', 5 ); // Priority 5 so it runs before the main action