diff --git a/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthEtIsolations.h b/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthEtIsolations.h
index 59b5c7ff998eeab1c18054ff2703338c6326048c..20be30414bf09d3f2fcec5138dc28ce8fcee9660 100644
--- a/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthEtIsolations.h
+++ b/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthEtIsolations.h
@@ -1,7 +1,7 @@
 ///////////////////////// -*- C++ -*- /////////////////////////////
 
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
 */
 
 // TruthEtIsolations.h 
@@ -197,7 +197,8 @@ class TruthEtIsolations
   /////////////////////////////////////////////////////////////////// 
   // Protected data: 
   /////////////////////////////////////////////////////////////////// 
- protected: 
+ protected:
+  friend class TruthEtIsolationsCnv_p1;
 
   /// @c ElementLink to the @c HepMC::GenEvent from which the Et isolations
   /// have been (or will be) computed
diff --git a/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthParticleContainer.h b/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthParticleContainer.h
index f52f7f3fda2eee66e1221d2c6fbfd349909c906b..bc14d8075330bae2843c99ebc505b0157134e46f 100644
--- a/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthParticleContainer.h
+++ b/PhysicsAnalysis/TruthParticleID/McParticleEvent/McParticleEvent/TruthParticleContainer.h
@@ -1,7 +1,7 @@
 ///////////////////////// -*- C++ -*- /////////////////////////////
 
 /*
-  Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
 */
 
 // TruthParticleContainer.h 
@@ -97,6 +97,11 @@ class TruthParticleContainer : public DataVector<TruthParticle>
    */
   const HepMC::GenEvent* genEvent() const;
 
+  /** Retrieve the @c HepMC::GenEvent this @c TruthParticleContainer
+   *  is proxying, as a link.
+   */
+  const ElementLink<McEventCollection>& genEventLink() const;
+
   /** Retrieve the name (@c StoreGate location) of the 
    *  @c HepMC::GenEvent this @c TruthParticleContainer is proxying
    */
@@ -136,6 +141,11 @@ class TruthParticleContainer : public DataVector<TruthParticle>
    */
   const TruthEtIsolations::EtIsol_t* etIsolations( const int barcode ) const;
 
+  /** 
+   * return the link to truth Et isolations.
+   */
+  const ElementLink<TruthEtIsolationsContainer>& etIsolationsLink() const;
+
   /**
    * Return the Et isolation for a given particle and a given cone size
    */
@@ -221,6 +231,13 @@ const HepMC::GenEvent* TruthParticleContainer::genEvent() const
   return m_genEvent.isValid() ? (*m_genEvent) : 0;
 }
 
+inline 
+const ElementLink<McEventCollection>&
+TruthParticleContainer::genEventLink() const
+{
+  return m_genEvent;
+}
+
 inline 
 std::size_t TruthParticleContainer::genEventIdx() const
 {
@@ -253,6 +270,12 @@ TruthParticleContainer::etIsolations( const int barcode ) const
     : 0;
 }
 
+inline const ElementLink<TruthEtIsolationsContainer>&
+TruthParticleContainer::etIsolationsLink() const
+{
+  return m_etIsolations;
+}
+
 inline double 
 TruthParticleContainer::etIsol( const int barcode,
 				const TruthParticleParameters::ConeSize idx ) const