diff --git a/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtils.java b/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtils.java
index fa2017e..de2f293 100644
--- a/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtils.java
+++ b/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtils.java
@@ -231,7 +231,8 @@ public interface CKanUtils {
 	boolean deleteDatasetRelationship(String datasetIdSubject, String datasetIdObject, DatasetRelationships relation, String apiKey);
 
 	/**
-	 * Returns the list of relationships between dataset datasetIdSubject and dataset datasetIdObject.
+	 * Returns the list of relationships between dataset datasetIdSubject and dataset datasetIdObject. If datasetIdObject is missing, the whole list of 
+	 * relationships for dataset datasetIdSubject is returned.
 	 * @param datasetIdSubject
 	 * @param datasetIdObject
 	 * @param apiKey
diff --git a/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtilsImpl.java b/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtilsImpl.java
index 9dd7a9d..066ca8a 100644
--- a/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtilsImpl.java
+++ b/src/main/java/org/gcube/datacatalogue/ckanutillibrary/CKanUtilsImpl.java
@@ -1009,16 +1009,15 @@ public class CKanUtilsImpl implements CKanUtils{
 		return false;
 	}
 
+	@SuppressWarnings("unchecked")
 	@Override
 	public List<CkanDatasetRelationship> getRelationshipDatasets(
 			String datasetIdSubject, String datasetIdObject, String apiKey) {
 
 		// checks
 		checkNotNull(datasetIdSubject);
-		checkNotNull(datasetIdObject);
 		checkNotNull(apiKey);
 		checkArgument(!datasetIdSubject.isEmpty());
-		checkArgument(!datasetIdObject.isEmpty());
 		checkArgument(!apiKey.isEmpty());
 
 		try(CloseableHttpClient httpClient = HttpClientBuilder.create().build();){
@@ -1028,17 +1027,25 @@ public class CKanUtilsImpl implements CKanUtils{
 			// we need to use the apis to make it
 			String path = "/api/3/action/package_relationships_list";
 
+			String parameter;
+
 			// Request parameters to be replaced
-			String parameter = "{"
-					+ "\"id\":\"SUBJECT\","
-					+ "\"id2\":\"OBJECT\""
-					+ "}";
+			if(datasetIdObject == null || datasetIdObject.isEmpty())
+				parameter = "{"
+						+ "\"id\":\"SUBJECT\""
+						+ "}";
+			else
+				parameter = "{"
+						+ "\"id\":\"SUBJECT\","
+						+ "\"id2\":\"OBJECT\""
+						+ "}";
 
 			// replace those values
 			parameter = parameter.replace("SUBJECT", datasetIdSubject);
-			parameter = parameter.replace("OBJECT", datasetIdObject);
+			if(datasetIdObject != null && !datasetIdObject.isEmpty())
+				parameter = parameter.replace("OBJECT", datasetIdObject);
 
-			logger.debug("API request for delete relationship is going to be " + parameter);
+			logger.debug("API request for getting relationship is going to be " + parameter);
 
 			HttpPost request = new HttpPost(CKAN_CATALOGUE_URL + path);
 			request.addHeader("Authorization", apiKey);
diff --git a/src/main/java/org/gcube/datacatalogue/ckanutillibrary/models/DatasetRelationships.java b/src/main/java/org/gcube/datacatalogue/ckanutillibrary/models/DatasetRelationships.java
index 24ba04c..f5cc75f 100644
--- a/src/main/java/org/gcube/datacatalogue/ckanutillibrary/models/DatasetRelationships.java
+++ b/src/main/java/org/gcube/datacatalogue/ckanutillibrary/models/DatasetRelationships.java
@@ -16,13 +16,12 @@ package org.gcube.datacatalogue.ckanutillibrary.models;
  * @author Costantino Perciante at ISTI-CNR (costantino.perciante@isti.cnr.it)
  */
 public enum DatasetRelationships {
-
 	depends_on,
-	//	dependency_of,
+	dependency_of,
 	derives_from,
-	//	has_derivation,
+	has_derivation,
 	child_of,
-	//	parent_of,
-	links_to
-	//	linked_from
+	parent_of,
+	links_to,
+	linked_from
 }
diff --git a/src/test/java/org/gcube/datacatalogue/ckanutillibrary/TestCKanLib.java b/src/test/java/org/gcube/datacatalogue/ckanutillibrary/TestCKanLib.java
index daa53a3..9546d79 100644
--- a/src/test/java/org/gcube/datacatalogue/ckanutillibrary/TestCKanLib.java
+++ b/src/test/java/org/gcube/datacatalogue/ckanutillibrary/TestCKanLib.java
@@ -21,6 +21,8 @@ public class TestCKanLib {
 	private CkanUtilsFactory factory;
 	private String scope = "/gcube/devsec/devVRE";
 	private String testUser = "costantino_perciante";
+	String subjectId = "aa_father4";
+	String objectId = "bb_son4";
 
 	//@Before
 	public void before(){
@@ -28,21 +30,25 @@ public class TestCKanLib {
 	}
 
 	//@Test
-	public void datasetsRelationshipCreateDelete() throws Exception{
+	public void datasetsRelationshipCreate() throws Exception{
 
 		CKanUtilsImpl instance = factory.getUtilsPerScope(scope);
 
-		String subjectId = "lucio_organization";
-		String objectId = "test_for_visibility";
-		DatasetRelationships relation = DatasetRelationships.depends_on;
+		DatasetRelationships relation = DatasetRelationships.parent_of;
 
 		boolean resC = instance.createDatasetRelationship(subjectId, objectId, relation, "Comment for this relationship", instance.getApiKeyFromUsername(testUser));
 
-		Thread.sleep(500);
+		logger.debug("Res is " + resC);
+	}
+
+	//@Test
+	public void datasetsRelationshipDelete() throws Exception{
+
+		CKanUtilsImpl instance = factory.getUtilsPerScope(scope);
+		DatasetRelationships relation = DatasetRelationships.child_of;
 
 		boolean resD = instance.deleteDatasetRelationship(subjectId, objectId, relation, instance.getApiKeyFromUsername(testUser));
 
-		logger.debug("ResC is " + resC);
 		logger.debug("ResD is " + resD);
 	}
 
@@ -51,9 +57,6 @@ public class TestCKanLib {
 
 		CKanUtilsImpl instance = factory.getUtilsPerScope(scope);
 
-		String subjectId = "lucio_organization";
-		String objectId = "test_for_visibility";
-
 		List<CkanDatasetRelationship> res = instance.getRelationshipDatasets(subjectId, objectId, instance.getApiKeyFromUsername(testUser));
 
 		logger.debug("Relationships " + res);