Filtering Admin Only Fields

I'm trying to filter the values of fields that are admin only and it's just not happening.
I've tried gform_replace_merge_tags, gform_pre_submission and maybe a couple of others... I've lost track.

One example is

add_filter('gform_replace_merge_tags', 'bmdo_merge_tags', 10, 7);
function bmdo_merge_tags($text, $form, $entry, $url_encode, $esc_html, $nl2br, $format) {

    $state = '{site_state}';
    $link = '{post_link}';

    if($state == $text)
        return $entry["9.4"];
    elseif ($link == $text)
    	return 'http://www.bushcaresmajordayout.org/?p='.$entry["post_id"];
    else
	    return $text;
}

None of them work, so I can only assume that it's because the two fields I'm trying to populate/modify are admin only.

The form is http://www.bushcaresmajordayout.org/register

Help greatly appreciated!

Handling via new support channel.