diff --git a/src/EntityTypeRelations.php b/src/EntityTypeRelations.php
new file mode 100644
index 0000000..e4f4742
--- /dev/null
+++ b/src/EntityTypeRelations.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace Drupal\opencase;
+
+/**
+ * Stuff to do with the relationship of case types to actor types, and activity types to case types
+ *
+ */
+class EntityTypeRelations {
+
+
+  public static function getAllowedParentBundles($childEntityType, $childBundle) {
+    $field = $childEntityType == 'oc_case' ? 'actors_involved' : 'oc_case';
+    $base_field_override = \Drupal\Core\Field\Entity\BaseFieldOverride::load("$childEntityType.$childBundle.$field");
+    $allowedBundles = array();
+    if ($base_field_override) { 
+      $actor_types =  $base_field_override->getSettings()['handler_settings']['target_bundles'];
+      // example of the $actor_types array: ['client' => 'client', 'volunteer' => 0]
+      foreach($actor_types as $machine_name => $value) {
+        if ($value) {
+          $allowedBundles[] = $machine_name;        
+        }
+      }
+    }
+    return $allowedBundles; // NB. this is an array of machine names only, indexed numerically.
+  }
+
+  public static function getAllowedChildBundles($parentEntityType, $parentBundle) {
+    $childEntityType = $parentEntityType == 'oc_case' ? 'oc_activity' : 'oc_case';
+    // get all the child bundles
+    $childBundles = \Drupal::service('entity_type.bundle.info')->getBundleInfo($childEntityType);
+    // $childBundles is array where the key is the machine name and the value is array containing label
+    $allowedChildBundles = array();
+    foreach(array_keys($childBundles) as $childBundle) {
+      if (in_array($parentBundle, self::getAllowedParentBundles($childEntityType, $childBundle))) {
+        $allowedChildBundles[$childBundle] = $childBundles[$childBundle]['label'];
+      }
+    }
+    return $allowedChildBundles; // NB. this is an array of labels, indexed by machine name.
+    
+  }
+}
diff --git a/src/EntityTypeRelationsWidget.php b/src/EntityTypeRelationsWidget.php
index e0a86de..6ba049c 100644
--- a/src/EntityTypeRelationsWidget.php
+++ b/src/EntityTypeRelationsWidget.php
@@ -39,17 +39,8 @@ class EntityTypeRelationsWidget {
    */ 
   public function populate(&$form) {
     $case_type_machine_name = $form['id']['#default_value'];
-    $base_field_override = \Drupal\Core\Field\Entity\BaseFieldOverride::load("oc_case.$case_type_machine_name.actors_involved");
-    if ($base_field_override) { 
-      $form['actor_types']['#default_value'] = array();
-      $actor_types =  $base_field_override->getSettings()['handler_settings']['target_bundles'];
-      // example of the $actor_types array: ['client' => 'client', 'volunteer' => 0]
-      foreach($actor_types as $machine_name => $value) {
-        if ($value) {
-          $form['actor_types']['#default_value'][] = $machine_name;        
-        }
-      }
-    }
+    $allowedParentBundles = EntityTypeRelations::getAllowedParentBundles('oc_case', $case_type_machine_name); 
+    $form['actor_types']['#default_value'] = $allowedParentBundles;
   }
   
   /**
diff --git a/src/Plugin/Block/ContextualMenu.php b/src/Plugin/Block/ContextualMenu.php
index b3c64b6..8f21cc6 100644
--- a/src/Plugin/Block/ContextualMenu.php
+++ b/src/Plugin/Block/ContextualMenu.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\opencase\Plugin\Block;
 
+use Drupal\opencase\EntityTypeRelations;
 use Drupal\Core\Block\BlockBase;
 use Drupal\Core\Link;
 use Drupal\Core\Url;
@@ -81,10 +82,13 @@ class ContextualMenu extends BlockBase {
   private function caseListPage() {
     $actor_id = \Drupal::routeMatch()->getParameter('actor_id');
     \Drupal::service('user.private_tempstore')->get('opencase')->set('actor_id', $actor_id);
-    $link = \Drupal::entityTypeManager()->getStorage('oc_actor')->load($actor_id)->toLink()->toString();
+    $actor = \Drupal::entityTypeManager()->getStorage('oc_actor')->load($actor_id);
+    $link = $actor->toLink()->toString();
     $markup = $this->asNavLinks([$link]);
     $current_path =  \Drupal::service('path.current')->getPath();
-    $markup .= $this->generateAddLinks('oc_case', "Add new case", ['actor_id' => $actor_id,  'destination' => $current_path]);
+    $title = "Add new case";
+    $query = ['actor_id' => $actor_id,  'destination' => $current_path];
+    $markup .= $this->generateLinksForAddingNewCases($actor, $title, $query);
     return $markup; 
   }
 
@@ -180,22 +184,15 @@ class ContextualMenu extends BlockBase {
   }
 
   /**
-   * Generates a set of links for adding different types of a base entity
-   *
-   * $baseEntityType the type of entity to generate the links for (it will generate one for each bundle of the base type)
-   * $title the title to be placed above the set of links)
-   * $query optionally append a query string to the links (key => value format
-   *
    * returns html markup.
    */
-  public static function generateAddLinks($baseEntityType, $title, $query = []) {
-    
-    $bundles = \Drupal::service('entity_type.bundle.info')->getBundleInfo($baseEntityType);
+  private function generateLinksForAddingNewCases($actor, $title, $query = []) {
+    $actor_type = $actor->bundle();
+    $allowedChildBundles = EntityTypeRelations::getAllowedChildBundles('oc_actor', $actor_type);
     $title = t($title); 
     $markup = "<h1>$title: </h1>";
-    foreach($bundles as $bundle_id => $bundle) {
-      $label = t($bundle['label']);
-      $url = \Drupal\Core\Url::fromRoute("entity.$baseEntityType.add_form", [$baseEntityType . '_type' => $bundle_id]);
+    foreach($allowedChildBundles as $machine_name => $label) {
+      $url = \Drupal\Core\Url::fromRoute("entity.oc_case.add_form", ['oc_case_type' => $machine_name]);
       $url->setOption('query', $query);
       $link = \Drupal\Core\Link::fromTextAndUrl($label, $url)->toString();
       $markup .= "<p>$link</p>";