diff --git a/doc/source/images/generate_diagram.py b/doc/source/images/generate_diagram.py
index 3bf873f5c..1168fb637 100644
--- a/doc/source/images/generate_diagram.py
+++ b/doc/source/images/generate_diagram.py
@@ -29,7 +29,6 @@ def get_rect_height(name, obj):
     nlines += len(getattr(obj, '_all_attrs', []))
     nlines += len(getattr(obj, '_single_child_objects', []))
     nlines += len(getattr(obj, '_multi_child_objects', []))
-    nlines += len(getattr(obj, '_multi_parent_objects', []))
     return nlines * line_heigth
 
 
@@ -100,8 +99,7 @@ def generate_diagram(filename, rect_pos, rect_width, figsize):
     for name, pos in rect_pos.items():
         htotal = all_h[name]
         obj = objs[name]
-        allrelationship = (list(getattr(obj, '_child_containers', []))
-                           + list(getattr(obj, '_multi_parent_containers', [])))
+        allrelationship = list(getattr(obj, '_child_containers', []))
 
         rect = Rectangle(pos, rect_width, htotal,
                          facecolor='w', edgecolor='k', linewidth=2.)
@@ -123,8 +121,7 @@ def generate_diagram(filename, rect_pos, rect_width, figsize):
         ax.add_patch(rect)
 
         # multi relationship
-        relationship = (list(getattr(obj, '_multi_child_objects', []))
-                        + list(getattr(obj, '_multi_parent_containers', [])))
+        relationship = list(getattr(obj, '_multi_child_objects', []))
         pos2 = (pos[1] + htotal - line_heigth * (1.5 + len(relationship))
                 - rect_height)
         rect_height = len(relationship) * line_heigth
diff --git a/neo/core/analogsignal.py b/neo/core/analogsignal.py
index 476b732c2..ac47834a3 100644
--- a/neo/core/analogsignal.py
+++ b/neo/core/analogsignal.py
@@ -160,8 +160,8 @@ class AnalogSignal(BaseSignal):
 
     '''
 
-    _single_parent_objects = ('Segment', 'ChannelIndex')
-    _single_parent_attrs = ('segment', 'channel_index')
+    _parent_objects = ('Segment', 'ChannelIndex')
+    _parent_attrs = ('segment', 'channel_index')
     _quantity_attr = 'signal'
     _necessary_attrs = (('signal', pq.Quantity, 2),
                         ('sampling_rate', pq.Quantity, 0),
diff --git a/neo/core/baseneo.py b/neo/core/baseneo.py
index f9e2120d6..bf92d8ee9 100644
--- a/neo/core/baseneo.py
+++ b/neo/core/baseneo.py
@@ -18,12 +18,6 @@
                             Number, Decimal,
                             np.number, np.bool_)
 
-# handle both Python 2 and Python 3
-try:
-    ALLOWED_ANNOTATION_TYPES += (long, unicode)
-except NameError:
-    pass
-
 logger = logging.getLogger("Neo")
 
 
@@ -179,20 +173,13 @@ class BaseNeo:
     and also sets up the :attr:`annotations` dict for additional arguments.
 
     Each class can define one or more of the following class attributes:
-        :_single_parent_objects: Neo objects that can be parents of this
-                                 object. This attribute is used in cases where
-                                 only one parent of this class is allowed.
-                                 An instance attribute named
-                                 class.__name__.lower() will be automatically
-                                 defined to hold this parent and will be
-                                 initialized to None.
-        :_multi_parent_objects: Neo objects that can be parents of this
-                                object. This attribute is used in cases where
-                                multiple parents of this class is allowed.
-                                An instance attribute named
-                                class.__name__.lower()+'s' will be
-                                automatically defined to hold this parent and
-                                will be initialized to an empty list.
+        :_parent_objects: Neo objects that can be parents of this
+                          object. Note that no Neo object can have
+                          more than one parent.
+                          An instance attribute named
+                          class.__name__.lower() will be automatically
+                          defined to hold this parent and will be
+                          initialized to None.
         :_necessary_attrs: A list of tuples containing the attributes that the
                            class must have. The tuple can have 2-4 elements.
                            The first element is the attribute name.
@@ -210,15 +197,8 @@ class must have. The tuple can have 2-4 elements.
                                    pretty-printing using iPython.
 
     The following helper properties are available:
-        :_parent_objects: All parent objects.
-                         :_single_parent_objects: + :_multi_parent_objects:
-        :_single_parent_containers: The names of the container attributes used
-                                   to store :_single_parent_objects:
-        :_multi_parent_containers: The names of the container attributes used
-                                   to store :_multi_parent_objects:
-        :_parent_containers: All parent container attributes.
-                            :_single_parent_containers: +
-                            :_multi_parent_containers:
+        :_parent_containers: The names of the container attributes used
+                             to store :_parent_objects:
         :parents: All objects that are parents of the current object.
         :_all_attrs: All required and optional attributes.
                      :_necessary_attrs: + :_recommended_attrs:
@@ -264,11 +244,9 @@ class attributes. :_recommended_attrs: should append
     # these attributes control relationships, they need to be
     # specified in each child class
     # Parent objects whose children can have a single parent
-    _single_parent_objects = ()
-    # Attribute names corresponding to _single_parent_objects
-    _single_parent_attrs = ()
-    # Parent objects whose children can have multiple parents
-    _multi_parent_objects = ()
+    _parent_objects = ()
+    # Attribute names corresponding to _parent_objects
+    _parent_attrs = ()
 
     # Attributes that an instance is required to have defined
     _necessary_attrs = ()
@@ -298,10 +276,8 @@ def __init__(self, name=None, description=None, file_origin=None,
         self.file_origin = file_origin
 
         # initialize parent containers
-        for parent in self._single_parent_containers:
+        for parent in self._parent_containers:
             setattr(self, parent, None)
-        for parent in self._multi_parent_containers:
-            setattr(self, parent, [])
 
     def annotate(self, **annotations):
         """
@@ -341,46 +317,21 @@ def _repr_pretty_(self, pp, cycle):
             pp.breakable()
             self._repr_pretty_attrs_(pp, cycle)
 
-    @property
-    def _single_parent_containers(self):
-        """
-        Containers for parent objects whose children can have a single parent.
-        """
-        return tuple([_reference_name(parent) for parent in
-                      self._single_parent_objects])
-
-    @property
-    def _multi_parent_containers(self):
-        """
-        Containers for parent objects whose children can have multiple parents.
-        """
-        return tuple([_container_name(parent) for parent in
-                      self._multi_parent_objects])
-
-    @property
-    def _parent_objects(self):
-        """
-        All types for parent objects.
-        """
-        return self._single_parent_objects + self._multi_parent_objects
-
     @property
     def _parent_containers(self):
         """
-        All containers for parent objects.
+        Containers for parent objects.
         """
-        return self._single_parent_containers + self._multi_parent_containers
+        return tuple([_reference_name(parent) for parent in
+                      self._parent_objects])
 
     @property
     def parents(self):
         """
         All parent objects storing the current object.
         """
-        single = [getattr(self, attr) for attr in
-                  self._single_parent_containers]
-        multi = [list(getattr(self, attr)) for attr in
-                 self._multi_parent_containers]
-        return tuple(single + sum(multi, []))
+        return tuple([getattr(self, attr) for attr in
+                      self._parent_containers])
 
     @property
     def _all_attrs(self):
@@ -420,9 +371,9 @@ def set_parent(self, obj):
         Set the appropriate "parent" attribute of this object
         according to the type of "obj"
         """
-        if obj.__class__.__name__ not in self._single_parent_objects:
+        if obj.__class__.__name__ not in self._parent_objects:
             raise TypeError("{} can only have parents of type {}, not {}".format(
-                self.__class__.__name__, self._single_parent_objects, obj.__class__.__name__))
-        loc = self._single_parent_objects.index(obj.__class__.__name__)
-        parent_attr = self._single_parent_attrs[loc]
+                self.__class__.__name__, self._parent_objects, obj.__class__.__name__))
+        loc = self._parent_objects.index(obj.__class__.__name__)
+        parent_attr = self._parent_attrs[loc]
         setattr(self, parent_attr, obj)
diff --git a/neo/core/channelindex.py b/neo/core/channelindex.py
index c15a843f0..14dd31d32 100644
--- a/neo/core/channelindex.py
+++ b/neo/core/channelindex.py
@@ -154,7 +154,7 @@ class ChannelIndex(Container):
 
     _container_child_objects = ('Unit',)
     _data_child_objects = ('AnalogSignal', 'IrregularlySampledSignal')
-    _single_parent_objects = ('Block',)
+    _parent_objects = ('Block',)
     _necessary_attrs = (('index', np.ndarray, 1, np.dtype('i')),)
     _recommended_attrs = ((('channel_names', np.ndarray, 1, np.dtype('U')),
                            ('channel_ids', np.ndarray, 1, np.dtype('i')),
diff --git a/neo/core/dataobject.py b/neo/core/dataobject.py
index 6fe687591..59d287a71 100644
--- a/neo/core/dataobject.py
+++ b/neo/core/dataobject.py
@@ -357,7 +357,7 @@ def __deepcopy__(self, memo):
             # thus creating a lot of overhead
             # But keeping the reference to the same parent is not desired either, because this would be unidirectional
             # When deepcopying top-down, e.g. a whole block, the links will be handled by the parent
-            if k in self._single_parent_attrs:
+            if k in self._parent_attrs:
                 setattr(new_obj, k, None)
                 continue
             try:
diff --git a/neo/core/epoch.py b/neo/core/epoch.py
index 092c58d51..95c68aff7 100644
--- a/neo/core/epoch.py
+++ b/neo/core/epoch.py
@@ -72,8 +72,8 @@ class Epoch(DataObject):
 
     '''
 
-    _single_parent_objects = ('Segment',)
-    _single_parent_attrs = ('segment',)
+    _parent_objects = ('Segment',)
+    _parent_attrs = ('segment',)
     _quantity_attr = 'times'
     _necessary_attrs = (('times', pq.Quantity, 1), ('durations', pq.Quantity, 1),
                         ('labels', np.ndarray, 1, np.dtype('U')))
diff --git a/neo/core/event.py b/neo/core/event.py
index 615860453..b0a765b12 100644
--- a/neo/core/event.py
+++ b/neo/core/event.py
@@ -65,8 +65,8 @@ class Event(DataObject):
 
     '''
 
-    _single_parent_objects = ('Segment',)
-    _single_parent_attrs = ('segment',)
+    _parent_objects = ('Segment',)
+    _parent_attrs = ('segment',)
     _quantity_attr = 'times'
     _necessary_attrs = (('times', pq.Quantity, 1), ('labels', np.ndarray, 1, np.dtype('U')))
 
diff --git a/neo/core/group.py b/neo/core/group.py
index 22cfc848d..7e88e81bf 100644
--- a/neo/core/group.py
+++ b/neo/core/group.py
@@ -42,7 +42,7 @@ class Group(Container):
         'Event', 'Epoch', 'ChannelView', 'ImageSequence'
     )
     _container_child_objects = ('Segment', 'Group')
-    _single_parent_objects = ('Block',)
+    _parent_objects = ('Block',)
 
     def __init__(self, objects=None, name=None, description=None, file_origin=None,
                  allowed_types=None, **annotations):
diff --git a/neo/core/imagesequence.py b/neo/core/imagesequence.py
index 5fd929ff4..e0ecbc311 100644
--- a/neo/core/imagesequence.py
+++ b/neo/core/imagesequence.py
@@ -86,8 +86,8 @@ class ImageSequence(BaseSignal):
             (:attr:`t_start` + :attr:`duration`)
      """
 
-    _single_parent_objects = ("Segment",)
-    _single_parent_attrs = ("segment",)
+    _parent_objects = ("Segment",)
+    _parent_attrs = ("segment",)
     _quantity_attr = "image_data"
     _necessary_attrs = (
         ("image_data", pq.Quantity, 3),
diff --git a/neo/core/irregularlysampledsignal.py b/neo/core/irregularlysampledsignal.py
index e0f5a79b0..609fa01de 100644
--- a/neo/core/irregularlysampledsignal.py
+++ b/neo/core/irregularlysampledsignal.py
@@ -123,8 +123,8 @@ class IrregularlySampledSignal(BaseSignal):
 
     '''
 
-    _single_parent_objects = ('Segment', 'ChannelIndex')
-    _single_parent_attrs = ('segment', 'channel_index')
+    _parent_objects = ('Segment', 'ChannelIndex')
+    _parent_attrs = ('segment', 'channel_index')
     _quantity_attr = 'signal'
     _necessary_attrs = (('times', pq.Quantity, 1), ('signal', pq.Quantity, 2))
 
diff --git a/neo/core/segment.py b/neo/core/segment.py
index a2b534e9e..20f87f15e 100644
--- a/neo/core/segment.py
+++ b/neo/core/segment.py
@@ -75,7 +75,7 @@ class Segment(Container):
     _data_child_objects = ('AnalogSignal',
                            'Epoch', 'Event',
                            'IrregularlySampledSignal', 'SpikeTrain', 'ImageSequence')
-    _single_parent_objects = ('Block',)
+    _parent_objects = ('Block',)
     _recommended_attrs = ((('file_datetime', datetime),
                            ('rec_datetime', datetime),
                            ('index', int)) +
diff --git a/neo/core/spiketrain.py b/neo/core/spiketrain.py
index f6a63ca64..58303d2af 100644
--- a/neo/core/spiketrain.py
+++ b/neo/core/spiketrain.py
@@ -199,8 +199,8 @@ class SpikeTrain(DataObject):
 
     '''
 
-    _single_parent_objects = ('Segment', 'Unit')
-    _single_parent_attrs = ('segment', 'unit')
+    _parent_objects = ('Segment', 'Unit')
+    _parent_attrs = ('segment', 'unit')
     _quantity_attr = 'times'
     _necessary_attrs = (('times', pq.Quantity, 1), ('t_start', pq.Quantity, 0),
                         ('t_stop', pq.Quantity, 0))
diff --git a/neo/core/unit.py b/neo/core/unit.py
index 19f068d81..2dceff365 100644
--- a/neo/core/unit.py
+++ b/neo/core/unit.py
@@ -56,7 +56,7 @@ class Unit(Container):
     '''
 
     _data_child_objects = ('SpikeTrain',)
-    _single_parent_objects = ('ChannelIndex',)
+    _parent_objects = ('ChannelIndex',)
     _recommended_attrs = Container._recommended_attrs
 
     def __init__(self, name=None, description=None, file_origin=None,
diff --git a/neo/core/view.py b/neo/core/view.py
index b42d17463..1254b909a 100644
--- a/neo/core/view.py
+++ b/neo/core/view.py
@@ -30,8 +30,8 @@ class ChannelView(BaseNeo):
     Note: Any other additional arguments are assumed to be user-specific
             metadata and stored in :attr:`annotations`.
     """
-    _single_parent_objects = ('Segment',)
-    _single_parent_attrs = ('segment',)
+    _parent_objects = ('Segment',)
+    _parent_attrs = ('segment',)
     _necessary_attrs = (
         ('index', np.ndarray, 1, np.dtype('i')),
         ('obj', ('AnalogSignal', 'IrregularlySampledSignal'), 1)
diff --git a/neo/io/proxyobjects.py b/neo/io/proxyobjects.py
index 820b9a067..1059b2918 100644
--- a/neo/io/proxyobjects.py
+++ b/neo/io/proxyobjects.py
@@ -80,7 +80,7 @@ class AnalogSignalProxy(BaseProxy):
     >>> some_channel_of_anasig = proxy_anasig.load(channel_indexes=[0,5,10])
 
     '''
-    _single_parent_objects = ('Segment', 'ChannelIndex')
+    _parent_objects = ('Segment', 'ChannelIndex')
     _necessary_attrs = (('sampling_rate', pq.Quantity, 0),
                                     ('t_start', pq.Quantity, 0))
     _recommended_attrs = BaseNeo._recommended_attrs
@@ -287,7 +287,7 @@ class SpikeTrainProxy(BaseProxy):
 
     '''
 
-    _single_parent_objects = ('Segment', 'Unit')
+    _parent_objects = ('Segment', 'Unit')
     _quantity_attr = 'times'
     _necessary_attrs = (('t_start', pq.Quantity, 0),
                                     ('t_stop', pq.Quantity, 0))
@@ -385,7 +385,7 @@ def load(self, time_slice=None, strict_slicing=True,
 
 
 class _EventOrEpoch(BaseProxy):
-    _single_parent_objects = ('Segment',)
+    _parent_objects = ('Segment',)
     _quantity_attr = 'times'
 
     def __init__(self, rawio=None, event_channel_index=None, block_index=0, seg_index=0):
diff --git a/neo/test/coretest/test_analogsignal.py b/neo/test/coretest/test_analogsignal.py
index de16b9ede..4212a5b75 100644
--- a/neo/test/coretest/test_analogsignal.py
+++ b/neo/test/coretest/test_analogsignal.py
@@ -339,11 +339,9 @@ def test__children(self):
         chx.analogsignals = [signal]
         chx.create_many_to_one_relationship()
 
-        self.assertEqual(signal._single_parent_objects, ('Segment', 'ChannelIndex'))
-        self.assertEqual(signal._multi_parent_objects, ())
+        self.assertEqual(signal._parent_objects, ('Segment', 'ChannelIndex'))
 
-        self.assertEqual(signal._single_parent_containers, ('segment', 'channel_index'))
-        self.assertEqual(signal._multi_parent_containers, ())
+        self.assertEqual(signal._parent_containers, ('segment', 'channel_index'))
 
         self.assertEqual(signal._parent_objects, ('Segment', 'ChannelIndex'))
         self.assertEqual(signal._parent_containers, ('segment', 'channel_index'))
diff --git a/neo/test/coretest/test_base.py b/neo/test/coretest/test_base.py
index bd7b010db..14d4325d2 100644
--- a/neo/test/coretest/test_base.py
+++ b/neo/test/coretest/test_base.py
@@ -116,11 +116,9 @@ def test_annotate(self):
     def test__children(self):
         base = BaseNeo()
 
-        self.assertEqual(base._single_parent_objects, ())
-        self.assertEqual(base._multi_parent_objects, ())
+        self.assertEqual(base._parent_objects, ())
 
-        self.assertEqual(base._single_parent_containers, ())
-        self.assertEqual(base._multi_parent_containers, ())
+        self.assertEqual(base._parent_containers, ())
 
         self.assertEqual(base._parent_objects, ())
         self.assertEqual(base._parent_containers, ())
diff --git a/neo/test/coretest/test_block.py b/neo/test/coretest/test_block.py
index 9e2b3c397..c7a4853f7 100644
--- a/neo/test/coretest/test_block.py
+++ b/neo/test/coretest/test_block.py
@@ -258,9 +258,8 @@ def test__children(self):
         self.assertEqual(self.blk1._container_child_objects,
                          ('Segment', 'ChannelIndex', 'Group'))
         self.assertEqual(self.blk1._data_child_objects, ())
-        self.assertEqual(self.blk1._single_parent_objects, ())
+        self.assertEqual(self.blk1._parent_objects, ())
         self.assertEqual(self.blk1._multi_child_objects, ())
-        self.assertEqual(self.blk1._multi_parent_objects, ())
         self.assertEqual(self.blk1._child_properties,
                          ('Unit',))
 
@@ -272,9 +271,8 @@ def test__children(self):
         self.assertEqual(self.blk1._data_child_containers, ())
         self.assertEqual(self.blk1._single_child_containers,
                          ('segments', 'channel_indexes', 'groups'))
-        self.assertEqual(self.blk1._single_parent_containers, ())
+        self.assertEqual(self.blk1._parent_containers, ())
         self.assertEqual(self.blk1._multi_child_containers, ())
-        self.assertEqual(self.blk1._multi_parent_containers, ())
 
         self.assertEqual(self.blk1._child_objects,
                          ('Segment', 'ChannelIndex', 'Group'))
diff --git a/neo/test/coretest/test_channelindex.py b/neo/test/coretest/test_channelindex.py
index 7a4b06fe5..05a0e4ab5 100644
--- a/neo/test/coretest/test_channelindex.py
+++ b/neo/test/coretest/test_channelindex.py
@@ -218,9 +218,8 @@ def test__children(self):
         self.assertEqual(self.chx1._container_child_objects, ('Unit',))
         self.assertEqual(self.chx1._data_child_objects,
                          ('AnalogSignal', 'IrregularlySampledSignal'))
-        self.assertEqual(self.chx1._single_parent_objects, ('Block',))
+        self.assertEqual(self.chx1._parent_objects, ('Block',))
         self.assertEqual(self.chx1._multi_child_objects, tuple())
-        self.assertEqual(self.chx1._multi_parent_objects, ())
         self.assertEqual(self.chx1._child_properties, ())
 
         self.assertEqual(self.chx1._single_child_objects,
@@ -231,10 +230,9 @@ def test__children(self):
                          ('analogsignals', 'irregularlysampledsignals'))
         self.assertEqual(self.chx1._single_child_containers,
                          ('units', 'analogsignals', 'irregularlysampledsignals'))
-        self.assertEqual(self.chx1._single_parent_containers, ('block',))
+        self.assertEqual(self.chx1._parent_containers, ('block',))
         self.assertEqual(self.chx1._multi_child_containers,
                          tuple())
-        self.assertEqual(self.chx1._multi_parent_containers, ())
 
         self.assertEqual(self.chx1._child_objects,
                          ('Unit', 'AnalogSignal', 'IrregularlySampledSignal'))
diff --git a/neo/test/coretest/test_container.py b/neo/test/coretest/test_container.py
index d156a896b..99296b197 100644
--- a/neo/test/coretest/test_container.py
+++ b/neo/test/coretest/test_container.py
@@ -47,11 +47,9 @@ def test_init(self):
 
     def test__children(self):
         container = Container()
-        self.assertEqual(container._single_parent_objects, ())
-        self.assertEqual(container._multi_parent_objects, ())
+        self.assertEqual(container._parent_objects, ())
 
-        self.assertEqual(container._single_parent_containers, ())
-        self.assertEqual(container._multi_parent_containers, ())
+        self.assertEqual(container._parent_containers, ())
 
         self.assertEqual(container._parent_objects, ())
         self.assertEqual(container._parent_containers, ())
diff --git a/neo/test/coretest/test_epoch.py b/neo/test/coretest/test_epoch.py
index c2c7935bb..a8c952b66 100644
--- a/neo/test/coretest/test_epoch.py
+++ b/neo/test/coretest/test_epoch.py
@@ -262,11 +262,9 @@ def test__children(self):
         segment.epochs = [epc]
         segment.create_many_to_one_relationship()
 
-        self.assertEqual(epc._single_parent_objects, ('Segment',))
-        self.assertEqual(epc._multi_parent_objects, ())
+        self.assertEqual(epc._parent_objects, ('Segment',))
 
-        self.assertEqual(epc._single_parent_containers, ('segment',))
-        self.assertEqual(epc._multi_parent_containers, ())
+        self.assertEqual(epc._parent_containers, ('segment',))
 
         self.assertEqual(epc._parent_objects, ('Segment',))
         self.assertEqual(epc._parent_containers, ('segment',))
diff --git a/neo/test/coretest/test_event.py b/neo/test/coretest/test_event.py
index db85048ac..c11dbde05 100644
--- a/neo/test/coretest/test_event.py
+++ b/neo/test/coretest/test_event.py
@@ -523,11 +523,9 @@ def test__children(self):
         segment.events = [evt]
         segment.create_many_to_one_relationship()
 
-        self.assertEqual(evt._single_parent_objects, ('Segment',))
-        self.assertEqual(evt._multi_parent_objects, ())
+        self.assertEqual(evt._parent_objects, ('Segment',))
 
-        self.assertEqual(evt._single_parent_containers, ('segment',))
-        self.assertEqual(evt._multi_parent_containers, ())
+        self.assertEqual(evt._parent_containers, ('segment',))
 
         self.assertEqual(evt._parent_objects, ('Segment',))
         self.assertEqual(evt._parent_containers, ('segment',))
diff --git a/neo/test/coretest/test_segment.py b/neo/test/coretest/test_segment.py
index b2d87c5a1..a0784a7fa 100644
--- a/neo/test/coretest/test_segment.py
+++ b/neo/test/coretest/test_segment.py
@@ -310,18 +310,16 @@ def test__children(self):
                       'imagesequences')
         self.assertEqual(self.seg1._container_child_objects, ())
         self.assertEqual(self.seg1._data_child_objects, childobjs)
-        self.assertEqual(self.seg1._single_parent_objects, ('Block',))
+        self.assertEqual(self.seg1._parent_objects, ('Block',))
         self.assertEqual(self.seg1._multi_child_objects, ())
-        self.assertEqual(self.seg1._multi_parent_objects, ())
         self.assertEqual(self.seg1._child_properties, ())
 
         self.assertEqual(self.seg1._single_child_objects, childobjs)
         self.assertEqual(self.seg1._container_child_containers, ())
         self.assertEqual(self.seg1._data_child_containers, childconts)
         self.assertEqual(self.seg1._single_child_containers, childconts)
-        self.assertEqual(self.seg1._single_parent_containers, ('block',))
+        self.assertEqual(self.seg1._parent_containers, ('block',))
         self.assertEqual(self.seg1._multi_child_containers, ())
-        self.assertEqual(self.seg1._multi_parent_containers, ())
 
         self.assertEqual(self.seg1._child_objects, childobjs)
         self.assertEqual(self.seg1._child_containers, childconts)
diff --git a/neo/test/coretest/test_spiketrain.py b/neo/test/coretest/test_spiketrain.py
index 9f8c8b344..9544e320e 100644
--- a/neo/test/coretest/test_spiketrain.py
+++ b/neo/test/coretest/test_spiketrain.py
@@ -2054,11 +2054,9 @@ def test__children(self):
         unit.spiketrains = [self.train1]
         unit.create_many_to_one_relationship()
 
-        self.assertEqual(self.train1._single_parent_objects, ('Segment', 'Unit'))
-        self.assertEqual(self.train1._multi_parent_objects, ())
+        self.assertEqual(self.train1._parent_objects, ('Segment', 'Unit'))
 
-        self.assertEqual(self.train1._single_parent_containers, ('segment', 'unit'))
-        self.assertEqual(self.train1._multi_parent_containers, ())
+        self.assertEqual(self.train1._parent_containers, ('segment', 'unit'))
 
         self.assertEqual(self.train1._parent_objects, ('Segment', 'Unit'))
         self.assertEqual(self.train1._parent_containers, ('segment', 'unit'))
diff --git a/neo/test/coretest/test_unit.py b/neo/test/coretest/test_unit.py
index 4919fdcf5..bf0a29efc 100644
--- a/neo/test/coretest/test_unit.py
+++ b/neo/test/coretest/test_unit.py
@@ -144,10 +144,9 @@ def test__children(self):
 
         self.assertEqual(self.unit1._container_child_objects, ())
         self.assertEqual(self.unit1._data_child_objects, ('SpikeTrain',))
-        self.assertEqual(self.unit1._single_parent_objects,
+        self.assertEqual(self.unit1._parent_objects,
                          ('ChannelIndex',))
         self.assertEqual(self.unit1._multi_child_objects, ())
-        self.assertEqual(self.unit1._multi_parent_objects, ())
         self.assertEqual(self.unit1._child_properties, ())
 
         self.assertEqual(self.unit1._single_child_objects, ('SpikeTrain',))
@@ -155,10 +154,9 @@ def test__children(self):
         self.assertEqual(self.unit1._container_child_containers, ())
         self.assertEqual(self.unit1._data_child_containers, ('spiketrains',))
         self.assertEqual(self.unit1._single_child_containers, ('spiketrains',))
-        self.assertEqual(self.unit1._single_parent_containers,
+        self.assertEqual(self.unit1._parent_containers,
                          ('channel_index',))
         self.assertEqual(self.unit1._multi_child_containers, ())
-        self.assertEqual(self.unit1._multi_parent_containers, ())
 
         self.assertEqual(self.unit1._child_objects, ('SpikeTrain',))
         self.assertEqual(self.unit1._child_containers, ('spiketrains',))