diff --git a/gtsam.h b/gtsam.h
index 2516cb202..171749a83 100644
--- a/gtsam.h
+++ b/gtsam.h
@@ -896,6 +896,7 @@ class SymbolicBayesNet {
   // Standard interface
   size_t size() const;
   void saveGraph(string s) const;
+  gtsam::SymbolicConditional* at(size_t idx) const;
   gtsam::SymbolicConditional* front() const;
   gtsam::SymbolicConditional* back() const;
   void push_back(gtsam::SymbolicConditional* conditional);
@@ -947,7 +948,7 @@ class SymbolicBayesTree {
 // //  BayesNet<ConditionalType> shortcut(derived_ptr root, Eliminate function) const;
 // //  FactorGraph<FactorType> marginal(derived_ptr root, Eliminate function) const;
 // //  FactorGraph<FactorType> joint(derived_ptr C2, derived_ptr root, Eliminate function) const;
-// 
+//
 //   void deleteCachedShortcuts();
 // };
 
@@ -1317,13 +1318,19 @@ class GaussianFactorGraph {
 
 #include <gtsam/linear/GaussianConditional.h>
 virtual class GaussianConditional : gtsam::GaussianFactor {
-    //Constructors
+  //Constructors
   GaussianConditional(size_t key, Vector d, Matrix R, const gtsam::noiseModel::Diagonal* sigmas);
   GaussianConditional(size_t key, Vector d, Matrix R, size_t name1, Matrix S,
       const gtsam::noiseModel::Diagonal* sigmas);
   GaussianConditional(size_t key, Vector d, Matrix R, size_t name1, Matrix S,
       size_t name2, Matrix T, const gtsam::noiseModel::Diagonal* sigmas);
 
+  //Constructors with no noise model
+  GaussianConditional(size_t key, Vector d, Matrix R);
+    GaussianConditional(size_t key, Vector d, Matrix R, size_t name1, Matrix S);
+    GaussianConditional(size_t key, Vector d, Matrix R, size_t name1, Matrix S,
+        size_t name2, Matrix T);
+
   //Standard Interface
   void print(string s) const;
   bool equals(const gtsam::GaussianConditional &cg, double tol) const;
@@ -1704,6 +1711,23 @@ class KeyVector {
   void serialize() const;
 };
 
+// Actually a FastMap<Key,int>
+class KeyGroupMap {
+  KeyGroupMap();
+
+  // Note: no print function
+
+  // common STL methods
+  size_t size() const;
+  bool empty() const;
+  void clear();
+
+  // structure specific methods
+  size_t at(size_t key) const;
+  int erase(size_t key);
+  bool insert2(size_t key, int val);
+};
+
 #include <gtsam/nonlinear/Marginals.h>
 class Marginals {
   Marginals(const gtsam::NonlinearFactorGraph& graph,
@@ -1959,6 +1983,7 @@ class ISAM2 {
   gtsam::ISAM2Result update();
   gtsam::ISAM2Result update(const gtsam::NonlinearFactorGraph& newFactors, const gtsam::Values& newTheta);
   gtsam::ISAM2Result update(const gtsam::NonlinearFactorGraph& newFactors, const gtsam::Values& newTheta, const gtsam::KeyVector& removeFactorIndices);
+  gtsam::ISAM2Result update(const gtsam::NonlinearFactorGraph& newFactors, const gtsam::Values& newTheta, const gtsam::KeyVector& removeFactorIndices, const gtsam::KeyGroupMap& constrainedKeys);
   // TODO: wrap the full version of update
  //void update(const gtsam::NonlinearFactorGraph& newFactors, const gtsam::Values& newTheta, const gtsam::KeyVector& removeFactorIndices, FastMap<Key,int>& constrainedKeys);
   //void update(const gtsam::NonlinearFactorGraph& newFactors, const gtsam::Values& newTheta, const gtsam::KeyVector& removeFactorIndices, FastMap<Key,int>& constrainedKeys, bool force_relinearize);
diff --git a/gtsam/base/FastMap.h b/gtsam/base/FastMap.h
index 2ef201b9d..084919427 100644
--- a/gtsam/base/FastMap.h
+++ b/gtsam/base/FastMap.h
@@ -60,6 +60,8 @@ public:
     return std::map<KEY,VALUE>(this->begin(), this->end());
   }
 
+  /** Handy 'insert' function for Matlab wrapper */
+  bool insert2(const KEY& key, const VALUE& val) { return Base::insert(std::make_pair<KEY,VALUE>(key, val)).second; }
   /** Handy 'exists' function */
   bool exists(const KEY& e) const { return this->find(e) != this->end(); }
 
diff --git a/gtsam/inference/Key.h b/gtsam/inference/Key.h
index 21f75e8d4..3f573fcce 100644
--- a/gtsam/inference/Key.h
+++ b/gtsam/inference/Key.h
@@ -24,6 +24,7 @@
 #include <gtsam/base/FastVector.h>
 #include <gtsam/base/FastList.h>
 #include <gtsam/base/FastSet.h>
+#include <gtsam/base/FastMap.h>
 
 namespace gtsam {
 
@@ -43,6 +44,7 @@ namespace gtsam {
   typedef FastList<Key> KeyList;
   typedef FastVector<Key> KeyVector;
   typedef FastSet<Key> KeySet;
+  typedef FastMap<Key,int> KeyGroupMap;
 
   /// Utility function to print sets of keys with optional prefix
   GTSAM_EXPORT void printKeySet(const KeySet& keys, const std::string& s = "",