diff --git a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java
index b5bca2e93..0c7903137 100644
--- a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java
+++ b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/common/ModelSupport.java
@@ -3,6 +3,9 @@ package eu.dnetlib.dhp.schema.common;
 
 import static com.google.common.base.Preconditions.checkArgument;
 
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -473,4 +476,25 @@ public class ModelSupport {
 	private static <T extends Oaf> String idFnForOafEntity(T t) {
 		return ((OafEntity) t).getId();
 	}
+
+	public static final String ISO8601FORMAT = "yyyy-MM-dd'T'HH:mm:ssZ";
+
+	public static String oldest(String dateA, String dateB) throws ParseException {
+
+		if (StringUtils.isBlank(dateA)) {
+			return dateB;
+		}
+		if (StringUtils.isBlank(dateB)) {
+			return dateA;
+		}
+		if (StringUtils.isNotBlank(dateA) && StringUtils.isNotBlank(dateB)) {
+
+			final Date a = new SimpleDateFormat(ISO8601FORMAT).parse(dateA);
+			final Date b = new SimpleDateFormat(ISO8601FORMAT).parse(dateB);
+
+			return a.before(b) ? dateA : dateB;
+		} else {
+			return null;
+		}
+	}
 }
diff --git a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Relation.java b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Relation.java
index 0de34dbec..8825d7137 100644
--- a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Relation.java
+++ b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Relation.java
@@ -1,8 +1,11 @@
 
 package eu.dnetlib.dhp.schema.oaf;
 
+import eu.dnetlib.dhp.schema.common.ModelSupport;
+
 import static com.google.common.base.Preconditions.checkArgument;
 
+import java.text.ParseException;
 import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -106,7 +109,7 @@ public class Relation extends Oaf {
 	}
 
 	public Boolean getValidated() {
-		return validated;
+		return Objects.nonNull(validated) && validated;
 	}
 
 	public void setValidated(Boolean validated) {
@@ -130,6 +133,13 @@ public class Relation extends Oaf {
 			Objects.equals(getSubRelType(), r.getSubRelType()), "subRelType(s) must be equal");
 		checkArgument(Objects.equals(getRelClass(), r.getRelClass()), "relClass(es) must be equal");
 
+		setValidated(getValidated() || r.getValidated());
+		try {
+			setValidationDate(ModelSupport.oldest(getValidationDate(), r.getValidationDate()));
+		} catch (ParseException e) {
+			throw new IllegalArgumentException(String.format("invalid validation date format in relation [s:%s, t:%s]: %s", getSource(), getTarget(), getValidationDate()));
+		}
+
 		super.mergeFrom(r);
 	}
 
diff --git a/dhp-schemas/src/test/java/eu/dnetlib/dhp/schema/oaf/MergeTest.java b/dhp-schemas/src/test/java/eu/dnetlib/dhp/schema/oaf/MergeTest.java
index f91646f2c..6ee5b9d85 100644
--- a/dhp-schemas/src/test/java/eu/dnetlib/dhp/schema/oaf/MergeTest.java
+++ b/dhp-schemas/src/test/java/eu/dnetlib/dhp/schema/oaf/MergeTest.java
@@ -63,6 +63,51 @@ public class MergeTest {
 		assertEquals(3, a.getSubject().size());
 	}
 
+	@Test
+	public void mergeRelationTest() {
+
+		Relation a = createRel(null, null);
+		Relation b = createRel(null, null);
+		a.mergeFrom(b);
+		assertEquals(a, b);
+
+		a = createRel(true, null);
+		b = createRel(null, null);
+		a.mergeFrom(b);
+		assertEquals(true, a.getValidated());
+
+		a = createRel(true, null);
+		b = createRel(false, null);
+		a.mergeFrom(b);
+		assertEquals(true, a.getValidated());
+
+		a = createRel(true, null);
+		b = createRel(true, "2016-04-05T12:41:19.202Z");
+		a.mergeFrom(b);
+		assertEquals("2016-04-05T12:41:19.202Z", a.getValidationDate());
+	}
+
+	@Test
+	public void mergeRelationTestParseException() {
+		assertThrows(IllegalArgumentException.class, () -> {
+			Relation a = createRel(true, "2016-04-05");
+			Relation b = createRel(true, "2016-04-05");
+			a.mergeFrom(b);
+		});
+	}
+
+	private Relation createRel(Boolean validated, String validationDate) {
+		Relation rel = new Relation();
+		rel.setSource("1");
+		rel.setTarget("2");
+		rel.setRelType("reltype");
+		rel.setSubRelType("subreltype");
+		rel.setRelClass("relclass");
+		rel.setValidated(validated);
+		rel.setValidationDate(validationDate);
+		return rel;
+	}
+
 	private KeyValue setKV(final String key, final String value) {
 
 		KeyValue k = new KeyValue();