diff --git a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/AbstractMdRecordToOafMapper.java b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/AbstractMdRecordToOafMapper.java
index 50fc89f04..37c479e5f 100644
--- a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/AbstractMdRecordToOafMapper.java
+++ b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/AbstractMdRecordToOafMapper.java
@@ -6,18 +6,19 @@ import static eu.dnetlib.dhp.schema.common.ModelConstants.*;
 
 import java.util.*;
 
-import com.google.common.collect.Lists;
-import eu.dnetlib.dhp.schema.oaf.utils.IdentifierFactory;
 import org.apache.commons.lang3.StringUtils;
 import org.dom4j.Document;
 import org.dom4j.DocumentFactory;
 import org.dom4j.DocumentHelper;
 import org.dom4j.Node;
 
+import com.google.common.collect.Lists;
+
 import eu.dnetlib.dhp.oa.graph.raw.common.VocabularyGroup;
 import eu.dnetlib.dhp.schema.common.LicenseComparator;
 import eu.dnetlib.dhp.schema.common.ModelConstants;
 import eu.dnetlib.dhp.schema.oaf.*;
+import eu.dnetlib.dhp.schema.oaf.utils.IdentifierFactory;
 
 public abstract class AbstractMdRecordToOafMapper {
 
@@ -152,7 +153,8 @@ public abstract class AbstractMdRecordToOafMapper {
 		return oafs;
 	}
 
-	private OafEntity createEntity(Document doc, String type, List<Instance> instances, KeyValue collectedFrom, DataInfo info, long lastUpdateTimestamp) {
+	private OafEntity createEntity(Document doc, String type, List<Instance> instances, KeyValue collectedFrom,
+		DataInfo info, long lastUpdateTimestamp) {
 		switch (type.toLowerCase()) {
 			case "publication":
 				final Publication p = new Publication();
diff --git a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/GenerateEntitiesApplication.java b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/GenerateEntitiesApplication.java
index 3568dc52a..7b13e500e 100644
--- a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/GenerateEntitiesApplication.java
+++ b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/GenerateEntitiesApplication.java
@@ -29,16 +29,7 @@ import eu.dnetlib.dhp.application.ArgumentApplicationParser;
 import eu.dnetlib.dhp.common.HdfsSupport;
 import eu.dnetlib.dhp.oa.graph.raw.common.VocabularyGroup;
 import eu.dnetlib.dhp.schema.common.ModelSupport;
-import eu.dnetlib.dhp.schema.oaf.Dataset;
-import eu.dnetlib.dhp.schema.oaf.Datasource;
-import eu.dnetlib.dhp.schema.oaf.Oaf;
-import eu.dnetlib.dhp.schema.oaf.OafEntity;
-import eu.dnetlib.dhp.schema.oaf.Organization;
-import eu.dnetlib.dhp.schema.oaf.OtherResearchProduct;
-import eu.dnetlib.dhp.schema.oaf.Project;
-import eu.dnetlib.dhp.schema.oaf.Publication;
-import eu.dnetlib.dhp.schema.oaf.Relation;
-import eu.dnetlib.dhp.schema.oaf.Software;
+import eu.dnetlib.dhp.schema.oaf.*;
 import eu.dnetlib.dhp.utils.ISLookupClientFactory;
 import eu.dnetlib.enabling.is.lookup.rmi.ISLookUpService;
 import scala.Tuple2;
@@ -124,7 +115,27 @@ public class GenerateEntitiesApplication {
 
 	private static Oaf merge(final Oaf o1, final Oaf o2) {
 		if (ModelSupport.isSubClass(o1, OafEntity.class)) {
-			((OafEntity) o1).mergeFrom((OafEntity) o2);
+			if (ModelSupport.isSubClass(o1, Result.class)) {
+				if (ModelSupport.isSubClass(o1, Publication.class)) {
+					((Publication) o1).mergeFrom((Publication) o2);
+				} else if (ModelSupport.isSubClass(o1, Dataset.class)) {
+					((Dataset) o1).mergeFrom((Dataset) o2);
+				} else if (ModelSupport.isSubClass(o1, Software.class)) {
+					((Software) o1).mergeFrom((Software) o2);
+				} else if (ModelSupport.isSubClass(o1, OtherResearchProduct.class)) {
+					((OtherResearchProduct) o1).mergeFrom((OtherResearchProduct) o2);
+				} else {
+					throw new RuntimeException("invalid Result subtype:" + o1.getClass().getCanonicalName());
+				}
+			} else if (ModelSupport.isSubClass(o1, Datasource.class)) {
+				((Datasource) o1).mergeFrom((Datasource) o2);
+			} else if (ModelSupport.isSubClass(o1, Organization.class)) {
+				((Organization) o1).mergeFrom((Organization) o2);
+			} else if (ModelSupport.isSubClass(o1, Project.class)) {
+				((Project) o1).mergeFrom((Project) o2);
+			} else {
+				throw new RuntimeException("invalid OafEntity subtype:" + o1.getClass().getCanonicalName());
+			}
 		} else if (ModelSupport.isSubClass(o1, Relation.class)) {
 			((Relation) o1).mergeFrom((Relation) o2);
 		} else {
diff --git a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OafToOafMapper.java b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OafToOafMapper.java
index 135fcc595..543d22eeb 100644
--- a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OafToOafMapper.java
+++ b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OafToOafMapper.java
@@ -10,7 +10,6 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import eu.dnetlib.dhp.schema.oaf.*;
 import org.apache.commons.lang3.StringUtils;
 import org.dom4j.Document;
 import org.dom4j.Element;
@@ -20,6 +19,7 @@ import com.google.common.collect.Lists;
 
 import eu.dnetlib.dhp.common.PacePerson;
 import eu.dnetlib.dhp.oa.graph.raw.common.VocabularyGroup;
+import eu.dnetlib.dhp.schema.oaf.*;
 
 public class OafToOafMapper extends AbstractMdRecordToOafMapper {
 
@@ -248,8 +248,8 @@ public class OafToOafMapper extends AbstractMdRecordToOafMapper {
 
 	@Override
 	protected List<Oaf> addOtherResultRels(
-			final Document doc,
-			final OafEntity entity) {
+		final Document doc,
+		final OafEntity entity) {
 
 		final String docId = entity.getId();
 		final List<Oaf> res = new ArrayList<>();
diff --git a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OdfToOafMapper.java b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OdfToOafMapper.java
index 522b3f247..0319cb89e 100644
--- a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OdfToOafMapper.java
+++ b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/raw/OdfToOafMapper.java
@@ -12,8 +12,6 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
-import eu.dnetlib.dhp.schema.common.ModelConstants;
-import eu.dnetlib.dhp.schema.oaf.*;
 import org.apache.commons.lang3.StringUtils;
 import org.dom4j.Document;
 import org.dom4j.Node;
@@ -22,6 +20,8 @@ import com.google.common.collect.Lists;
 
 import eu.dnetlib.dhp.common.PacePerson;
 import eu.dnetlib.dhp.oa.graph.raw.common.VocabularyGroup;
+import eu.dnetlib.dhp.schema.common.ModelConstants;
+import eu.dnetlib.dhp.schema.oaf.*;
 
 public class OdfToOafMapper extends AbstractMdRecordToOafMapper {
 
@@ -306,8 +306,8 @@ public class OdfToOafMapper extends AbstractMdRecordToOafMapper {
 
 	@Override
 	protected List<Oaf> addOtherResultRels(
-			final Document doc,
-			final OafEntity entity) {
+		final Document doc,
+		final OafEntity entity) {
 
 		final String docId = entity.getId();
 
diff --git a/dhp-workflows/dhp-graph-mapper/src/test/java/eu/dnetlib/dhp/oa/graph/raw/MappersTest.java b/dhp-workflows/dhp-graph-mapper/src/test/java/eu/dnetlib/dhp/oa/graph/raw/MappersTest.java
index 2f5466d49..788ac09bc 100644
--- a/dhp-workflows/dhp-graph-mapper/src/test/java/eu/dnetlib/dhp/oa/graph/raw/MappersTest.java
+++ b/dhp-workflows/dhp-graph-mapper/src/test/java/eu/dnetlib/dhp/oa/graph/raw/MappersTest.java
@@ -11,8 +11,6 @@ import java.io.IOException;
 import java.util.List;
 import java.util.Optional;
 
-import eu.dnetlib.dhp.schema.oaf.*;
-import eu.dnetlib.dhp.schema.oaf.utils.IdentifierFactory;
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.junit.jupiter.api.BeforeEach;
@@ -26,6 +24,8 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import eu.dnetlib.dhp.oa.graph.clean.CleaningFunctionTest;
 import eu.dnetlib.dhp.oa.graph.raw.common.VocabularyGroup;
 import eu.dnetlib.dhp.schema.common.ModelConstants;
+import eu.dnetlib.dhp.schema.oaf.*;
+import eu.dnetlib.dhp.schema.oaf.utils.IdentifierFactory;
 import eu.dnetlib.enabling.is.lookup.rmi.ISLookUpService;
 
 @ExtendWith(MockitoExtension.class)