diff --git a/SimDataFormats/GeneratorProducts/interface/HepMC3Product.h b/SimDataFormats/GeneratorProducts/interface/HepMC3Product.h
index ca4c165c5950c..38b232f36067b 100644
--- a/SimDataFormats/GeneratorProducts/interface/HepMC3Product.h
+++ b/SimDataFormats/GeneratorProducts/interface/HepMC3Product.h
@@ -9,6 +9,8 @@
 #include "DataFormats/Common/interface/Ref.h"
 #include <TMatrixD.h>
 #include <HepMC3/GenEvent.h>
+#include <HepMC3/GenParticle.h>
+#include <HepMC3/GenVertex.h>
 #include <cstddef>
 
 namespace HepMC3 {
@@ -57,11 +59,11 @@ namespace edm {
   // This allows edm::Refs to work with HepMC3Product
   namespace refhelper {
     template <>
-    struct FindTrait<edm::HepMC3Product, HepMC3::GenParticle> {
+    struct FindTrait<edm::HepMC3Product, HepMC3::GenParticlePtr> {
       struct Find {
         using first_argument_type = edm::HepMC3Product const &;
         using second_argument_type = int;
-        using result_type = HepMC3::GenParticle const *;
+        using result_type = HepMC3::GenParticlePtr const *;
 
         result_type operator()(first_argument_type iContainer, second_argument_type iBarCode) {
           //return iContainer.getHepMCData().barcode_to_particle(iBarCode);
@@ -73,11 +75,11 @@ namespace edm {
     };
 
     template <>
-    struct FindTrait<edm::HepMC3Product, HepMC3::GenVertex> {
+    struct FindTrait<edm::HepMC3Product, HepMC3::GenVertexPtr> {
       struct Find {
         using first_argument_type = edm::HepMC3Product const &;
         using second_argument_type = int;
-        using result_type = HepMC3::GenVertex const *;
+        using result_type = HepMC3::GenVertexPtr const *;
 
         result_type operator()(first_argument_type iContainer, second_argument_type iBarCode) {
           //return iContainer.getHepMCData().barcode_to_vertex(iBarCode);
diff --git a/SimDataFormats/GeneratorProducts/src/classes.h b/SimDataFormats/GeneratorProducts/src/classes.h
index f4ef658588213..47319d29706ad 100644
--- a/SimDataFormats/GeneratorProducts/src/classes.h
+++ b/SimDataFormats/GeneratorProducts/src/classes.h
@@ -11,16 +11,21 @@
 #include "SimDataFormats/GeneratorProducts/interface/LHEXMLStringProduct.h"
 
 #include "SimDataFormats/GeneratorProducts/interface/HepMCProduct.h"
+#include "SimDataFormats/GeneratorProducts/interface/HepMC3Product.h"
 
 #include "SimDataFormats/GeneratorProducts/interface/GenRunInfoProduct.h"
 #include "SimDataFormats/GeneratorProducts/interface/GenFilterInfo.h"
 #include "SimDataFormats/GeneratorProducts/interface/GenEventInfoProduct.h"
+#include "SimDataFormats/GeneratorProducts/interface/GenEventInfoProduct3.h"
 #include "SimDataFormats/GeneratorProducts/interface/GenLumiInfoProduct.h"
 #include "SimDataFormats/GeneratorProducts/interface/GenLumiInfoHeader.h"
 #include "SimDataFormats/GeneratorProducts/interface/ExternalGeneratorLumiInfo.h"
 #include "SimDataFormats/GeneratorProducts/interface/ExternalGeneratorEventInfo.h"
 
 #include <HepMC/GenRanges.h>
+#include <HepMC3/GenVertex.h>
+#include <HepMC3/GenParticle.h>
+#include <HepMC3/Attribute.h>
 
 //needed for backward compatibility between HepMC 2.06.xx and 2.05.yy
 namespace hepmc_rootio {
diff --git a/SimDataFormats/GeneratorProducts/src/classes_def.xml b/SimDataFormats/GeneratorProducts/src/classes_def.xml
index 8713c2309ca58..95056c4cd959f 100644
--- a/SimDataFormats/GeneratorProducts/src/classes_def.xml
+++ b/SimDataFormats/GeneratorProducts/src/classes_def.xml
@@ -97,6 +97,36 @@
 	<class name="std::pair&lt;int,HepMC::GenParticle*&gt;"/>
 	<class name="std::map&lt;int,HepMC::GenVertex*,std::greater&lt;int&gt; &gt;"/>
 
+
+
+
+        <!-- HepMC3 externals -->
+        <class name="HepMC3::GenEvent"/>
+        <class name="HepMC3::GenVertex"/>
+        <class name="HepMC3::GenParticle"/>
+
+        <!-- HepMC3Product -->
+
+        <class name="edm::Wrapper&lt;edm::HepMC3Product&gt;"/>
+        <class name="std::vector&lt;const edm::HepMC3Product*&gt;"/>
+	<!--
+        <class name="edm::Ref&lt;edm::HepMC3Product,HepMC3::GenVertex,edm::refhelper::FindTrait&lt;edm::HepMC3Product,HepMC3::GenVertex&gt;::Find&gt;"/>
+        <class name="edm::Ref&lt;edm::HepMC3Product,HepMC3::GenParticle,edm::refhelper::FindTrait&lt;edm::HepMC3Product,HepMC3::GenParticle&gt;::Find&gt;"/>
+        <class name="edm::RefVector&lt;edm::HepMC3Product,HepMC3::GenVertex,edm::refhelper::FindTrait&lt;edm::HepMC3Product,HepMC3::GenVertex&gt;::Find&gt;"/>
+        <class name="edm::RefVector&lt;edm::HepMC3Product,HepMC3::GenParticle,edm::refhelper::FindTrait&lt;edm::HepMC3Product,HepMC3::GenParticle&gt;::Find&gt;"/>
+	-->
+        <class name="std::map&lt;int,HepMC3::GenVertex*&gt;"/>
+        <class name="std::pair&lt;const int,HepMC3::GenVertex*&gt;"/>
+        <class name="std::pair&lt;int,HepMC3::GenVertex*&gt;"/>
+        <class name="std::map&lt;int,HepMC3::GenParticle*&gt;"/>
+        <class name="std::pair&lt;const int,HepMC3::GenParticle*&gt;"/>
+        <class name="std::pair&lt;int,HepMC3::GenParticle*&gt;"/>
+        <class name="std::map&lt;int,HepMC3::GenVertex*,std::greater&lt;int&gt; &gt;"/>
+
+
+
+
+
 	<!-- Classes shared between different kinds of products -->
 
         <class name="gen::PdfInfo" ClassVersion="10">
@@ -185,6 +215,17 @@
  </ioread> 
 	<class name="edm::Wrapper&lt;GenEventInfoProduct&gt;"/>
 
+
+
+
+        <!-- GenEventInfoProduct3 -->
+        <class name="GenEventInfoProduct3"/>
+        <class name="edm::Wrapper<GenEventInfoProduct3>"/>
+
+
+
+
+
 	<!-- LHE products -->
 
 	<class name="lhef::HEPEUP::FiveVector" ClassVersion="10">