diff --git a/library/Businessprocess/BpNode.php b/library/Businessprocess/BpNode.php
index 895836e..49a1421 100644
--- a/library/Businessprocess/BpNode.php
+++ b/library/Businessprocess/BpNode.php
@@ -3,7 +3,6 @@
 namespace Icinga\Module\Businessprocess;
 
 use Icinga\Exception\ConfigurationError;
-use Icinga\Exception\ProgrammingError;
 
 class BpNode extends Node
 {
@@ -14,8 +13,12 @@ class BpNode extends Node
     protected $url;
     protected $info_command;
     protected $display = 0;
+
+    /** @var  Node[] */
     protected $children;
-    protected $child_names = array();
+
+    /** @var array */
+    protected $childNames = array();
     protected $alias;
     protected $counters;
     protected $missing = null;
@@ -89,6 +92,30 @@ class BpNode extends Node
         return false;
     }
 
+    /**
+     * @param Node $node
+     * @return $this
+     * @throws ConfigurationError
+     */
+    public function addChild(Node $node)
+    {
+        if ($this->children === null) {
+            $this->getChildren();
+        }
+
+        $name = (string) $node;
+        if (array_key_exists($name, $this->children)) {
+            throw new ConfigurationError(
+                'Node "%s" has been defined more than once',
+                $name
+            );
+        }
+        $this->children[$name] = $node;
+        $this->children[] = $name;
+        $node->addParent($this);
+        return $this;
+    }
+
     public function getProblematicChildren()
     {
         $problems = array();
@@ -304,26 +331,32 @@ class BpNode extends Node
     public function setChildNames($names)
     {
         sort($names);
-        $this->child_names = $names;
+        $this->childNames = $names;
         $this->children = null;
         return $this;
     }
 
+    public function hasChildren($filter = null)
+    {
+        return !empty($this->childNames);
+    }
+
     public function getChildNames()
     {
-        return $this->child_names;
+        return $this->childNames;
     }
 
     public function getChildren($filter = null)
     {
         if ($this->children === null) {
             $this->children = array();
-            natsort($this->child_names);
-            foreach ($this->child_names as $name) {
+            natsort($this->childNames);
+            foreach ($this->childNames as $name) {
                 $this->children[$name] = $this->bp->getNode($name);
                 $this->children[$name]->addParent($this);
             }
         }
+
         return $this->children;
     }
 
diff --git a/library/Businessprocess/Node.php b/library/Businessprocess/Node.php
index 6636db8..96fdfef 100644
--- a/library/Businessprocess/Node.php
+++ b/library/Businessprocess/Node.php
@@ -142,21 +142,6 @@ abstract class Node
         return false;
     }
 
-    public function addChild(Node $node)
-    {
-        if (array_key_exists((string) $node, $this->children)) {
-            throw new Exception(
-                sprintf(
-                    'Node "%s" has been defined more than once',
-                    $node
-                )
-            );
-        }
-        $this->childs[(string) $node] = $node;
-        $node->addParent($this);
-        return $this;
-    }
-
     public function setState($state)
     {
         $this->state = (int) $state;