Displaying Items on Child- but not on Parentpages

Hello,

I am using wordpress as a homepage for an upcoming event. Depending on how much sponsors are paying, their logo shall be shown on some but not on all pages. The theme i am using contains the following code:

function nichtAufSeite($pageName){
		$this->pages[]=$pageName;
	}

	function displayOK($pageName){
		if (count($this->pages)==0) return true;
		if (in_array($pageName,$this->pages)) return false;
		return true;

	}

A sponsor can be added with the folling entry:

$sponsor = new Sponsor();
$sponsor->name ='SPONSOREN';
$sponsor->uri ='www.myurl.de/';
$sponsor->bild ='sponsoren.png';
$sponsor->mouseOverBild ='sponsoren.png';
<ul>$sponsor->nichtAufSeite('start');</ul>
$sponsors[]=$sponsor;

The underlined items tell WP on what page this particular sponsor shall not be show.

However, lets say the page “start” has some child pages. How do I have to modify the code, so that the sponsor is not show on the page “start” but is shown on the page “start/childpage” ?

Thanks in advance.