diff --git a/browser/concept.py b/browser/concept.py
index c2459ed..0380335 100644
--- a/browser/concept.py
+++ b/browser/concept.py
@@ -88,9 +88,9 @@ class ConceptView(BaseView):
                 predicate = self.loopsRoot.loopsTraverse(relToken)
                 qualifier = self.request.get('qualifier')
                 if qualifier == 'parents':
-                    self.context.deassignParents(concept, [predicate])
+                    self.context.deassignParent(concept, [predicate])
                 elif qualifier == 'children':
-                    self.context.deassignChildren(concept, [predicate])
+                    self.context.deassignChild(concept, [predicate])
                 else:
                     raise(BadRequest, 'Illegal qualifier: %s.' % qualifier)
             else:
diff --git a/concept.py b/concept.py
index ba9a646..0f5ae10 100644
--- a/concept.py
+++ b/concept.py
@@ -98,7 +98,7 @@ class Concept(Contained, Persistent):
         if current != concept:
             typePred = self.getConceptManager().getTypePredicate()
             if current is not None:
-                self.deassignParents(current, [typePred])
+                self.deassignParent(current, [typePred])
             self.assignParent(concept, typePred)
             #cm = self.getLoopsRoot().getConceptManager()
             #typeRelation = ConceptRelation(removeSecurityProxy(concept), self,
@@ -117,20 +117,20 @@ class Concept(Contained, Persistent):
 
     # concept relations
 
-    def getChildRelations(self, predicates=None, second=None):
+    def getChildRelations(self, predicates=None, child=None):
         predicates = predicates is None and ['*'] or predicates
         relationships = [ConceptRelation(self, None, p) for p in predicates]
         # TODO: sort...
-        return getRelations(first=self, second=second, relationships=relationships)
+        return getRelations(first=self, second=child, relationships=relationships)
 
     def getChildren(self, predicates=None):
         return [r.second for r in self.getChildRelations(predicates)]
 
-    def getParentRelations (self, predicates=None, first=None):
+    def getParentRelations (self, predicates=None, parent=None):
         predicates = predicates is None and ['*'] or predicates
         relationships = [ConceptRelation(None, self, p) for p in predicates]
         # TODO: sort...
-        return getRelations(first=first, second=self, relationships=relationships)
+        return getRelations(first=parent, second=self, relationships=relationships)
         
     def getParents(self, predicates=None):
         return [r.first for r in self.getParentRelations(predicates)]
@@ -146,25 +146,25 @@ class Concept(Contained, Persistent):
     def assignParent(self, concept, predicate=None):
         concept.assignChild(self, predicate)
 
-    def deassignChildren(self, concept, predicates=None):
+    def deassignChild(self, child, predicates=None):
         registry = zapi.getUtility(IRelationRegistry)
         #relations = []
         #for rs in relationships:
         #    relations.extend(registry.query(first=self, second=concept,
         #                                    relationship=rs))
-        for rel in self.getChildRelations(predicates, concept):
+        for rel in self.getChildRelations(predicates, child):
             registry.unregister(rel)
 
-    def deassignParents(self, concept, predicates=None):
-        concept.deassignChildren(self, predicates)
+    def deassignParent(self, parent, predicates=None):
+        parent.deassignChild(self, predicates)
     
     # resource relations
 
-    def getResourceRelations(self, predicates=None):
+    def getResourceRelations(self, predicates=None, resource=None):
         predicates = predicates is None and ['*'] or predicates
         relationships = [ResourceRelation(self, None, p) for p in predicates]
         # TODO: sort...
-        return getRelations(first=self, relationships=relationships)
+        return getRelations(first=self, second=resource, relationships=relationships)
 
     def getResources(self, predicates=None):
         return [r.second for r in self.getResourceRelations(predicates)]
@@ -178,7 +178,7 @@ class Concept(Contained, Persistent):
 
     def deassignResource(self, resource, predicates=None):
         registry = zapi.getUtility(IRelationRegistry)
-        for rel in self.getResourceRelations(predicates):
+        for rel in self.getResourceRelations(predicates, resource):
             registry.unregister(rel)
 
 
diff --git a/interfaces.py b/interfaces.py
index 981f5f1..4f34728 100644
--- a/interfaces.py
+++ b/interfaces.py
@@ -84,9 +84,10 @@ class IConcept(ILoopsObject, IPotentialTarget):
             optionally restricted to the predicates given.
         """
 
-    def getChildRelations(predicates=None):
+    def getChildRelations(predicates=None, children=None):
         """ Return a sequence of relations to other concepts assigned to self
-            as child concepts, optionally restricted to the predicates given.
+            as child concepts, optionally restricted to the predicates given
+            or to a certain child concept.
         """
 
     def getParents(predicates=None):
@@ -94,9 +95,10 @@ class IConcept(ILoopsObject, IPotentialTarget):
             optionally restricted to the predicates given.
         """
 
-    def getParentRelations(predicates=None):
+    def getParentRelations(predicates=None, parents=None):
         """ Return a sequence of relations to other concepts assigned to self
-            as child concepts, optionally restricted to the predicates given.
+            as parent concepts, optionally restricted to the predicates given
+            or to a certain parent concept.
         """
 
     def assignChild(concept, predicate):
@@ -113,13 +115,13 @@ class IConcept(ILoopsObject, IPotentialTarget):
             The predicate defaults to the concept manager's default predicate.
         """
 
-    def deassignChildren(concept, predicates=None):
+    def deassignChild(child, predicates=None):
         """ Remove the child concept relations to the concept given from self,
             optionally restricting them to the predicates given.
         """
 
-    def deassignParents(concept, predicates=None):
-        """ Remove the child concept relations to the concept given from self,
+    def deassignParent(parent, predicates=None):
+        """ Remove the parent concept relations to the concept given from self,
             optionally restricting them to the predicates given.
         """
 
@@ -128,9 +130,10 @@ class IConcept(ILoopsObject, IPotentialTarget):
             optionally restricted to the predicates given.
         """        
 
-    def getResourceRelations(predicates=None):
+    def getResourceRelations(predicates=None, resource=None):
         """ Return a sequence of relations to resources assigned to self,
-            optionally restricted to the predicates given.
+            optionally restricted to the predicates given or to a certain
+            resource.
         """
 
     def assignResource(resource, predicate):