diff --git a/core/project_hierarchy_api.php b/core/project_hierarchy_api.php
index 2a667d062e..5188080fda 100644
--- a/core/project_hierarchy_api.php
+++ b/core/project_hierarchy_api.php
@@ -30,9 +30,9 @@
  
 /**
  * Add project to project hierarchy
- * @param int $p_child_id
- * @param int $p_parent_id
- * @param bool $p_inherit_parent
+ * @param int $p_child_id Child project ID
+ * @param int $p_parent_id Parent project ID
+ * @param bool $p_inherit_parent Whether or not the child project inherits from the parent project
  * @return null
  */
 function project_hierarchy_add( $p_child_id, $p_parent_id, $p_inherit_parent = true ) {
@@ -56,9 +56,9 @@ function project_hierarchy_add( $p_child_id, $p_parent_id, $p_inherit_parent = t
 
 /**
  * Update project hierarchy
- * @param int $p_child_id
- * @param int $p_parent_id
- * @param bool $p_inherit_parent
+ * @param int $p_child_id Child project ID
+ * @param int $p_parent_id Parent project ID
+ * @param bool $p_inherit_parent Whether or not the child project inherits from the parent project
  * @return null
  */
 function project_hierarchy_update( $p_child_id, $p_parent_id, $p_inherit_parent = true ) {
@@ -77,8 +77,8 @@ function project_hierarchy_update( $p_child_id, $p_parent_id, $p_inherit_parent
 
 /**
  * Remove project from project hierarchy
- * @param int $p_child_id
- * @param int $p_parent_id
+ * @param int $p_child_id Child project ID
+ * @param int $p_parent_id Parent project ID
  * @return null
  */
 function project_hierarchy_remove( $p_child_id, $p_parent_id ) {
@@ -96,7 +96,7 @@ function project_hierarchy_remove( $p_child_id, $p_parent_id ) {
 
 /**
  * Remove any project hierarchy entries relating to project_id
- * @param int $p_project_id
+ * @param int $p_project_id Project ID
  * @return null
  */
 function project_hierarchy_remove_all( $p_project_id ) {
@@ -113,14 +113,15 @@ function project_hierarchy_remove_all( $p_project_id ) {
 
 /**
  * Returns true if project is at top of hierarchy
- * @param bool $p_project_id
+ * @param bool $p_project_id Project ID
+ * @param bool $p_show_disabled Whether or not to consider projects which are disabled
  * @return bool
  */
-function project_hierarchy_is_toplevel( $p_project_id ) {
+function project_hierarchy_is_toplevel( $p_project_id, $p_show_disabled = false ) {
 	global $g_cache_project_hierarchy;
 
-	if( null === $g_cache_project_hierarchy ) {
-		project_hierarchy_cache();
+	if( ( null === $g_cache_project_hierarchy ) || ( $p_show_disabled ) ) {
+		project_hierarchy_cache( $p_show_disabled );
 	}
 
 	if( isset( $g_cache_project_hierarchy[ALL_PROJECTS] ) ) {
@@ -131,8 +132,8 @@ function project_hierarchy_is_toplevel( $p_project_id ) {
 }
 
 /**
- * cache project hierarchy
- * @param bool $p_show_disabled
+ * Cache project hierarchy
+ * @param bool $p_show_disabled Whether or not to cache projects which are disabled
  * @return bool
  */
 function project_hierarchy_cache( $p_show_disabled = false ) {
@@ -191,26 +192,35 @@ function project_hierarchy_cache( $p_show_disabled = false ) {
 
 /**
  * Returns true if the child project inherits categories from the parent.
- * @param int $p_child_id
- * @param int $p_parent_id
- * @todo what happens if cache isn't populated?
+ * @param int $p_child_id Child project ID
+ * @param int $p_parent_id Parent project ID
+ * @param bool $p_show_disabled Whether or not to consider projects which are disabled
  * @return bool
  */
-function project_hierarchy_inherit_parent( $p_child_id, $p_parent_id ) {
+function project_hierarchy_inherit_parent( $p_child_id, $p_parent_id, $p_show_disabled = false ) {
 	global $g_cache_project_inheritance;
 
+	if( ( null === $g_cache_project_inheritance ) || ( $p_show_disabled ) ) {
+		project_hierarchy_cache( $p_show_disabled );
+	}
+
 	return in_array( $p_parent_id, $g_cache_project_inheritance[$p_child_id] );
 }
 
 /**
  * Generate an array of project's the given project inherits from,
  * including the original project in the result.
- * @param int $p_project_id
+ * @param int $p_project_id Project ID
+ * @param bool $p_show_disabled Whether or not to consider projects which are disabled
  * @return array
  */
-function project_hierarchy_inheritance( $p_project_id ) {
+function project_hierarchy_inheritance( $p_project_id, $p_show_disabled = false ) {
 	global $g_cache_project_inheritance;
 
+	if( ( null === $g_cache_project_inheritance ) || ( $p_show_disabled ) ) {
+		project_hierarchy_cache( $p_show_disabled );
+	}
+
 	$t_project_ids = array(
 		(int) $p_project_id,
 	);
@@ -241,14 +251,14 @@ function project_hierarchy_inheritance( $p_project_id ) {
 
 /**
  * Get subprojects for a project
- * @param int $p_project_id
- * @param bool $p_show_disabled
+ * @param int $p_project_id Project ID
+ * @param bool $p_show_disabled Whether or not to consider projects which are disabled
  * @return array
  */
 function project_hierarchy_get_subprojects( $p_project_id, $p_show_disabled = false ) {
 	global $g_cache_project_hierarchy;
 
-	if(( null === $g_cache_project_hierarchy ) || ( $p_show_disabled ) ) {
+	if( ( null === $g_cache_project_hierarchy ) || ( $p_show_disabled ) ) {
 		project_hierarchy_cache( $p_show_disabled );
 	}
 
@@ -261,7 +271,7 @@ function project_hierarchy_get_subprojects( $p_project_id, $p_show_disabled = fa
 
 /**
  * Get complete subproject hierarchy for a project
- * @param int $p_project_id
+ * @param int $p_project_id Project ID
  * @return array
  */
 function project_hierarchy_get_all_subprojects( $p_project_id ) {
diff --git a/manage_proj_edit_page.php b/manage_proj_edit_page.php
index f7f6428fb0..36e91b9cb5 100644
--- a/manage_proj_edit_page.php
+++ b/manage_proj_edit_page.php
@@ -195,7 +195,7 @@
 <?php echo form_security_field( 'manage_proj_update_children' ) ?>
 <input type="hidden" name="project_id" value="<?php echo $f_project_id ?>" />
 <?php
-	project_hierarchy_cache();
+	project_hierarchy_cache( true );
 	$t_subproject_ids = current_user_get_accessible_subprojects( $f_project_id, /* show_disabled */ true );
 
 	if ( Array() != $t_subproject_ids ) {
@@ -227,7 +227,7 @@
 <?php
 		foreach ( $t_subproject_ids as $t_subproject_id ) {
 			$t_subproject = project_get_row( $t_subproject_id );
-			$t_inherit_parent = project_hierarchy_inherit_parent( $t_subproject_id, $f_project_id );
+			$t_inherit_parent = project_hierarchy_inherit_parent( $t_subproject_id, $f_project_id, true );
 ?>
 <tr <?php echo helper_alternate_class() ?>>
 	<td>