A simple helper function for WordPress to check wether a post has grandchildren. Takes 1 parameter of a post id. Returns boolean (true or false)

Check if post has grandchildren.php

function has_grandchildren( $post_id ){
	
	$children = get_children(array(
		'post_parent' => $post_id
	));
	
	if( $children ){
		foreach( $children as $child ){
			$grandchildren = get_children(array(
				'post_parent' => $child->ID
			));
			if( $grandchildren ){
				return true;
			}
		}
	}
	
	return false;
	
}


// Example usage
if( has_grandchildren( $post_id ) ){
	//We have grandchildren!
}else{
	//Sorry no grandchildre..
}