Gravity Forms | Add a hidden field that pulls in value of another field and then prepends or appends additional text to it

gravity-forms-hidden-field-prepend-append-value.php

<?php

// Change 6 on the following to your form id number.
add_action( 'gform_pre_submission_6', 'pre_submission_handler' );
function pre_submission_handler( $form ) {
    // Change 145 to be the Hidden Field id number and 114_6 to the Last Name id number
    // which you can get while inspecting the fields in the backend of the Gravity Form while editing it
    $_POST['input_145'] = rgpost( 'input_114_6' ) . ' - Household';
}