diff --git a/openfpga/src/fabric/module_manager.cpp b/openfpga/src/fabric/module_manager.cpp
index d03af54b0..3f5cfdbfb 100644
--- a/openfpga/src/fabric/module_manager.cpp
+++ b/openfpga/src/fabric/module_manager.cpp
@@ -626,6 +626,18 @@ void ModuleManager::add_configurable_child(const ModuleId& parent_module,
   configurable_child_instances_[parent_module].push_back(child_instance);
 }
 
+void ModuleManager::reserve_configurable_child(const ModuleId& parent_module,
+                                               const size_t& num_children) {
+  VTR_ASSERT ( valid_module_id(parent_module) );
+  /* Do reserve when the number of children is larger than current size of lists */
+  if (num_children > configurable_children_[parent_module].size()) {
+    configurable_children_[parent_module].reserve(num_children);
+  }
+  if (num_children > configurable_child_instances_[parent_module].size()) {
+    configurable_child_instances_[parent_module].reserve(num_children);
+  }
+}
+
 /* Add a net to the connection graph of the module */ 
 ModuleNetId ModuleManager::create_module_net(const ModuleId& module) {
   /* Validate the module id */
@@ -741,6 +753,16 @@ ModuleNetSinkId ModuleManager::add_module_net_sink(const ModuleId& module, const
   return net_sink;
 }
 
+/******************************************************************************
+ * Public Deconstructor
+ ******************************************************************************/
+void ModuleManager::clear_configurable_children(const ModuleId& parent_module) {
+  VTR_ASSERT(valid_module_id(parent_module));
+
+  configurable_children_[parent_module].clear();
+  configurable_child_instances_[parent_module].clear();
+}
+
 /******************************************************************************
  * Private validators/invalidators
  ******************************************************************************/
diff --git a/openfpga/src/fabric/module_manager.h b/openfpga/src/fabric/module_manager.h
index cd79bde8c..ee06f1415 100644
--- a/openfpga/src/fabric/module_manager.h
+++ b/openfpga/src/fabric/module_manager.h
@@ -156,6 +156,11 @@ class ModuleManager {
     void set_child_instance_name(const ModuleId& parent_module, const ModuleId& child_module, const size_t& instance_id, const std::string& instance_name);
     /* Add a configurable child module to module */
     void add_configurable_child(const ModuleId& module, const ModuleId& child_module, const size_t& child_instance);
+    /* Reserved a number of configurable children
+     * for memory efficiency
+     */
+    void reserve_configurable_child(const ModuleId& module, const size_t& num_children);
+
     /* Add a net to the connection graph of the module */ 
     ModuleNetId create_module_net(const ModuleId& module);
     /* Set the name of net */
@@ -169,6 +174,13 @@ class ModuleManager {
     ModuleNetSinkId add_module_net_sink(const ModuleId& module, const ModuleNetId& net,
                                         const ModuleId& sink_module, const size_t& instance_id,
                                         const ModulePortId& sink_port, const size_t& sink_pin);
+  public: /* Public deconstructors */
+    /* This is a strong function which will remove all the configurable children 
+     * under a given parent module
+     * It is mainly used by loading fabric keys
+     * Do NOT use unless you know what you are doing!!!
+     */
+    void clear_configurable_children(const ModuleId& parent_module);
   public: /* Public validators/invalidators */
     bool valid_module_id(const ModuleId& module) const;
     bool valid_module_port_id(const ModuleId& module, const ModulePortId& port) const;