diff --git a/README.md b/README.md
index c820546..5236b02 100644
--- a/README.md
+++ b/README.md
@@ -83,3 +83,12 @@ Add support for Netbox 3.5 which become the minimum version supported to accomod
 
 * [#60](https://github.com/mlebreuil/netbox-contract/issues/60) Update contract quick search to also filter on fields "External reference" and "Comments".
 * [#49](https://github.com/mlebreuil/netbox-contract/issues/49) Manage permissions.
+
+#### version 2.0.4
+
+* Add bulk update capability for contract assignement
+* [#63](https://github.com/mlebreuil/netbox-contract/issues/63) Correct an API issue on the invoice object.
+* [#64](https://github.com/mlebreuil/netbox-contract/issues/64) Add hierarchy to contract; New parent field created.
+* [#65](https://github.com/mlebreuil/netbox-contract/issues/65) Add end date to contact import form.
+* Removed the possibility of add or modify circuits to contracts. The field becomes read only and will be removed in next major release.
+* Make accounting dimensions optional.
diff --git a/assignement_import.csv b/assignement_import.csv
new file mode 100644
index 0000000..3d9e213
--- /dev/null
+++ b/assignement_import.csv
@@ -0,0 +1,2 @@
+content_type,object_id,contract
+devices.device,1,3
\ No newline at end of file
diff --git a/contract.csv b/contract.csv
new file mode 100644
index 0000000..56dd46d
--- /dev/null
+++ b/contract.csv
@@ -0,0 +1,2 @@
+name,external_partie,internal_partie,tenant,status,start_date,end_date,mrc,nrc,invoice_frequency
+Contract10,ServiceProvider1,Nagra USA,Tenant1,Active,2023-06-01,2024-05-30,100,1000,1
diff --git a/pyproject.toml b/pyproject.toml
index cdfb8d8..5618c1d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "netbox-contract"
-version = "2.0.3"
+version = "2.0.4"
 authors = [
   { name="Marc Lebreuil", email="marc@famillelebreuil.net" },
 ]
diff --git a/src/netbox_contract/__init__.py b/src/netbox_contract/__init__.py
index 44b515c..66d3d74 100644
--- a/src/netbox_contract/__init__.py
+++ b/src/netbox_contract/__init__.py
@@ -4,7 +4,7 @@ class ContractsConfig(PluginConfig):
     name = 'netbox_contract'
     verbose_name = 'Netbox contract'
     description = 'Contract management plugin for Netbox'
-    version = '2.0.3'
+    version = '2.0.4'
     author = 'Marc Lebreuil'
     author_email = 'marc@famillelebreuil.net'
     base_url = 'contracts'
diff --git a/src/netbox_contract/api/serializers.py b/src/netbox_contract/api/serializers.py
index dca290a..1a9b47c 100644
--- a/src/netbox_contract/api/serializers.py
+++ b/src/netbox_contract/api/serializers.py
@@ -50,11 +50,12 @@ class ContractSerializer(NetBoxModelSerializer):
     )
     circuit= NestedCircuitSerializer(many=True, required=False)
     external_partie = NestedServiceProviderSerializer(many=False)
+    parent = NestedContracSerializer(many=False, required=False)
 
     class Meta:
         model = Contract
         fields = (
-            'id', 'url','display', 'name', 'status', 'external_partie','internal_partie','circuit','comments',
+            'id', 'url','display', 'name', 'status', 'external_partie','internal_partie','parent','circuit','comments',
             'tags', 'custom_fields', 'created', 'last_updated',
         )
 
diff --git a/src/netbox_contract/api/views.py b/src/netbox_contract/api/views.py
index 7ac1c56..9a5fd15 100644
--- a/src/netbox_contract/api/views.py
+++ b/src/netbox_contract/api/views.py
@@ -4,12 +4,14 @@
 from .serializers import ContractSerializer, InvoiceSerializer, ServiceProviderSerializer, ContractAssignementSerializer
 
 class ContractViewSet(NetBoxModelViewSet):
-    queryset = models.Contract.objects.prefetch_related('circuit','tags')
+    queryset = models.Contract.objects.prefetch_related(
+        'parent','circuit','tags'
+        )
     serializer_class = ContractSerializer
 
 class InvoiceViewSet(NetBoxModelViewSet):
     queryset = models.Invoice.objects.prefetch_related(
-        'contract', 'tags'
+        'contracts', 'tags'
     )
     serializer_class = InvoiceSerializer
     filterset_class = filtersets.InvoiceFilterSet
diff --git a/src/netbox_contract/filtersets.py b/src/netbox_contract/filtersets.py
index 2cfe177..dbfb748 100644
--- a/src/netbox_contract/filtersets.py
+++ b/src/netbox_contract/filtersets.py
@@ -7,7 +7,7 @@ class ContractFilterSet(NetBoxModelFilterSet):
 
     class Meta:
         model = Contract
-        fields = ('id', 'external_partie', 'internal_partie', 'status','circuit')
+        fields = ('id', 'external_partie', 'internal_partie', 'status','parent','circuit')
 
     def search(self, queryset, name, value):
         return queryset.filter( Q(name__icontains=value)
diff --git a/src/netbox_contract/forms.py b/src/netbox_contract/forms.py
index 796c1ca..594f0e9 100644
--- a/src/netbox_contract/forms.py
+++ b/src/netbox_contract/forms.py
@@ -1,27 +1,33 @@
 from django import forms
+from django.contrib.contenttypes.models import ContentType
 import django_filters
 from netbox.forms import NetBoxModelForm, NetBoxModelFilterSetForm, NetBoxModelBulkEditForm, NetBoxModelImportForm
-from utilities.forms.fields import CommentField, DynamicModelChoiceField, DynamicModelMultipleChoiceField, MultipleChoiceField, CSVModelChoiceField, SlugField
+from utilities.forms.fields import CommentField, DynamicModelChoiceField, DynamicModelMultipleChoiceField, MultipleChoiceField, CSVModelChoiceField, SlugField, CSVContentTypeField
 from utilities.forms.widgets import DatePicker
 from extras.filters import TagFilter
 from circuits.models import Circuit
+from tenancy.models import Tenant
 from .models import Contract, Invoice, ServiceProvider, StatusChoices, ContractAssignement
 
 class ContractForm(NetBoxModelForm):
     comments = CommentField()
-    circuit=DynamicModelMultipleChoiceField(
-        queryset=Circuit.objects.all(),
-        required=False
-    )
+
     external_partie=DynamicModelChoiceField(
         queryset=ServiceProvider.objects.all()
     )
+    tenant=DynamicModelChoiceField(
+        queryset=Tenant.objects.all()
+    )
+    parent=DynamicModelChoiceField(
+        queryset=Contract.objects.all(),
+        required=False
+    )
 
     class Meta:
         model = Contract
         fields = ('name', 'external_partie', 'external_reference', 'internal_partie','tenant', 'status',
           'start_date', 'end_date','initial_term', 'renewal_term', 'currency','accounting_dimensions',
-          'mrc', 'nrc','invoice_frequency','circuit', 'documents', 'comments', 'tags')
+          'mrc', 'nrc','invoice_frequency','parent','documents', 'comments', 'tags')
 
         widgets = {
             'start_date': DatePicker(),
@@ -46,10 +52,14 @@ class Meta:
 
 class ContractFilterSetForm(NetBoxModelFilterSetForm):
     model = Contract
-    external_partie=DynamicModelMultipleChoiceField(
+    external_partie=DynamicModelChoiceField(
         queryset=ServiceProvider.objects.all(),
         required=False
     )
+    tenant=DynamicModelChoiceField(
+        queryset=Tenant.objects.all(),
+        required=False
+    )
     external_reference=forms.CharField(
         required=False
     )
@@ -64,6 +74,10 @@ class ContractFilterSetForm(NetBoxModelFilterSetForm):
         queryset=Circuit.objects.all(),
         required=False
     )
+    parent=DynamicModelChoiceField(
+        queryset=Contract.objects.all(),
+        required=False
+    )
 
 class InvoiceFilterSetForm(NetBoxModelFilterSetForm):
     model = Invoice
@@ -73,18 +87,30 @@ class InvoiceFilterSetForm(NetBoxModelFilterSetForm):
     )
 
 class ContractCSVForm(NetBoxModelImportForm):
-    circuit = CSVModelChoiceField(
-        queryset=Circuit.objects.all(),
+    external_partie = CSVModelChoiceField(
+        queryset=ServiceProvider.objects.all(),
+        to_field_name='name',
+        help_text='Service provider name'
+    )
+    tenant = CSVModelChoiceField(
+        queryset=Tenant.objects.all(),
+        to_field_name='name',
+        help_text='Tenant name',
+        required=False
+    )
+    parent = CSVModelChoiceField(
+        queryset=Contract.objects.all(),
         to_field_name='name',
-        help_text='Related Circuit'
+        help_text='Contract name',
+        required=False
     )
 
     class Meta:
         model = Contract
         fields = [
             'name', 'external_partie', 'internal_partie','tenant', 'status',
-            'start_date', 'initial_term', 'renewal_term', 'mrc', 'nrc',
-            'invoice_frequency', 'circuit'
+            'start_date', 'end_date','initial_term', 'renewal_term', 'mrc', 'nrc',
+            'invoice_frequency', 'parent'
         ]
 
 class ContractBulkEditForm(NetBoxModelBulkEditForm):
@@ -92,9 +118,9 @@ class ContractBulkEditForm(NetBoxModelBulkEditForm):
         max_length=100,
         required=True
     )
-    external_partie = forms.CharField(
-        max_length=30,
-        required=True
+    external_partie = DynamicModelChoiceField(
+        queryset=ServiceProvider.objects.all(),
+        required=False
     )
     external_reference=forms.CharField(
         max_length=100,
@@ -106,7 +132,12 @@ class ContractBulkEditForm(NetBoxModelBulkEditForm):
     )
     comments = CommentField()
     circuit=DynamicModelChoiceField(
-        queryset=Circuit.objects.all()
+        queryset=Circuit.objects.all(),
+        required=False
+    )
+    parent = DynamicModelChoiceField(
+        queryset=Contract.objects.all(),
+        required=False
     )
 
     nullable_fields = (
@@ -181,6 +212,7 @@ class ContractAssignementForm(NetBoxModelForm):
     contract=DynamicModelChoiceField(
         queryset=Contract.objects.all()
     )
+
     class Meta:
         model = ContractAssignement
         fields = ['content_type', 'object_id', 'contract','tags']
@@ -194,3 +226,16 @@ class ContractAssignementFilterSetForm(NetBoxModelFilterSetForm):
     contract=DynamicModelChoiceField(
         queryset=Contract.objects.all()
     )
+
+class ContractAssignementImportForm(NetBoxModelImportForm):
+    content_type = CSVContentTypeField(
+        queryset=ContentType.objects.all(),
+        help_text="Content Type in the form <app>.<model>"
+    )
+    contract = CSVModelChoiceField(
+        queryset=Contract.objects.all(),
+        help_text="Contract id"
+    )
+    class Meta:
+        model = ContractAssignement
+        fields = ['content_type', 'object_id', 'contract','tags']
diff --git a/src/netbox_contract/migrations/0016_contract_parent.py b/src/netbox_contract/migrations/0016_contract_parent.py
new file mode 100644
index 0000000..eead24f
--- /dev/null
+++ b/src/netbox_contract/migrations/0016_contract_parent.py
@@ -0,0 +1,25 @@
+# Generated by Django 4.1.9 on 2023-06-18 14:45
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("netbox_contract", "0015_contractassignement"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="contract",
+            name="parent",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="child",
+                to="netbox_contract.contract",
+            ),
+        ),
+    ]
diff --git a/src/netbox_contract/migrations/0017_alter_contract_accounting_dimensions.py b/src/netbox_contract/migrations/0017_alter_contract_accounting_dimensions.py
new file mode 100644
index 0000000..d99ae60
--- /dev/null
+++ b/src/netbox_contract/migrations/0017_alter_contract_accounting_dimensions.py
@@ -0,0 +1,18 @@
+# Generated by Django 4.1.9 on 2023-06-18 16:05
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("netbox_contract", "0016_contract_parent"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="contract",
+            name="accounting_dimensions",
+            field=models.JSONField(blank=True, null=True),
+        ),
+    ]
diff --git a/src/netbox_contract/models.py b/src/netbox_contract/models.py
index 6254d51..33e0f2a 100644
--- a/src/netbox_contract/models.py
+++ b/src/netbox_contract/models.py
@@ -145,7 +145,8 @@ class Contract(NetBoxModel):
         default=CurrencyChoices.CURRENCY_USD
     )
     accounting_dimensions = models.JSONField(
-        null=True
+        null=True,
+        blank=True
     )
     mrc = models.DecimalField(
         verbose_name = "Monthly recuring cost",
@@ -164,7 +165,7 @@ class Contract(NetBoxModel):
     )
     circuit = models.ManyToManyField(Circuit,
         related_name='contracts',
-        blank=True,
+        blank=True
     )
     documents = models.URLField(
         blank=True
@@ -172,6 +173,13 @@ class Contract(NetBoxModel):
     comments = models.TextField(
         blank=True
     )
+    parent = models.ForeignKey(
+        'self',
+        on_delete=models.CASCADE,
+        related_name='child',
+        null=True,
+        blank=True
+    )
 
     def get_absolute_url(self):
         return reverse('plugins:netbox_contract:contract', args=[self.pk])
diff --git a/src/netbox_contract/navigation.py b/src/netbox_contract/navigation.py
index 6cef3c8..0a468e6 100644
--- a/src/netbox_contract/navigation.py
+++ b/src/netbox_contract/navigation.py
@@ -54,8 +54,13 @@
         buttons=serviceprovider_buttons,
         permissions=['netbox_contract.view_serviceprovider']
     )
+contract_assignemnt_menu_item = PluginMenuItem(
+        link='plugins:netbox_contract:contractassignement_list',
+        link_text='Contract assignements',
+        permissions=['netbox_contract.view_contractassignement']
+    )
 
-items = (contract_menu_item,invoices_menu_item,service_provider_menu_item)
+items = (contract_menu_item,invoices_menu_item,service_provider_menu_item, contract_assignemnt_menu_item)
 
 if plugin_settings.get("top_level_menu"):
     menu = PluginMenu(
diff --git a/src/netbox_contract/tables.py b/src/netbox_contract/tables.py
index ab9b899..397f1c9 100644
--- a/src/netbox_contract/tables.py
+++ b/src/netbox_contract/tables.py
@@ -63,13 +63,16 @@ class ContractListTable(NetBoxTable):
         linkify=True
     )
     circuit = tables.ManyToManyColumn()
+    parent = tables.Column(
+        linkify=True
+    )
 
     class Meta(NetBoxTable.Meta):
         model = Contract
         fields = ('pk', 'id', 'name', 'circuit', 'external_partie',
          'external_reference','internal_partie', 'status', 'mrc',
-         'comments', 'actions')
-        default_columns = ('name', 'status', 'circuit')
+         'parent','comments', 'actions')
+        default_columns = ('name', 'status', 'parent','circuit')
 
 class ContractListBottomTable(NetBoxTable):
     name = tables.Column(
diff --git a/src/netbox_contract/templates/netbox_contract/contract.html b/src/netbox_contract/templates/netbox_contract/contract.html
index 708b560..19981bd 100644
--- a/src/netbox_contract/templates/netbox_contract/contract.html
+++ b/src/netbox_contract/templates/netbox_contract/contract.html
@@ -73,6 +73,12 @@ <h5 class="card-header">Contract</h5>
               <th scope="row">Invoice frequency</th>
               <td>{{ object.invoice_frequency }}</td>
             </tr>
+            <tr>
+              <th scope="row">Parent</th>
+              <td>
+                <a href="{{ object.parent.get_absolute_url }}">{{ object.parent.name }}</a>
+              </td>
+            </tr>
             {% if object.documents %}
             <tr>
               <th scope="row">Documents</th>
diff --git a/src/netbox_contract/urls.py b/src/netbox_contract/urls.py
index 83bb29a..03c6afd 100644
--- a/src/netbox_contract/urls.py
+++ b/src/netbox_contract/urls.py
@@ -45,6 +45,7 @@
     # Contract assignements
     path('assignements/', views.ContractAssignementListView.as_view(), name='contractassignement_list'),
     path('assignements/add/', views.ContractAssignementEditView.as_view(), name='contractassignement_add'),
+    path('assignements/import/', views.ContractAssignementBulkImportView.as_view(), name='contractassignement_import'),
     path('assignements/<int:pk>/', views.ContractAssignementView.as_view(), name='contractassignement'),
     path('assignements/<int:pk>/edit/', views.ContractAssignementEditView.as_view(), name='contractassignement_edit'),
     path('assignements/<int:pk>/delete/', views.ContractAssignementDeleteView.as_view(), name='contractassignement_delete'),
diff --git a/src/netbox_contract/views.py b/src/netbox_contract/views.py
index b0dd3a6..05f6fc5 100644
--- a/src/netbox_contract/views.py
+++ b/src/netbox_contract/views.py
@@ -60,7 +60,7 @@ class ContractAssignementEditView(generic.ObjectEditView):
     form = forms.ContractAssignementForm
 
     def alter_object(self, instance, request, args, kwargs):
-        if not instance.pk:
+        if not instance.pk and kwargs:
             # Assign the object based on URL kwargs
             content_type = get_object_or_404(ContentType, pk=request.GET.get('content_type'))
             instance.object = get_object_or_404(content_type.model_class(), pk=request.GET.get('object_id'))
@@ -75,6 +75,11 @@ def get_extra_addanother_params(self, request):
 class ContractAssignementDeleteView(generic.ObjectDeleteView):
     queryset = models.ContractAssignement.objects.all()
 
+class ContractAssignementBulkImportView(generic.BulkImportView):
+    queryset = models.ContractAssignement.objects.all()
+    model_form = forms.ContractAssignementImportForm
+    table = tables.ContractAssignementListTable
+
 # Contract views
 
 class ContractView(generic.ObjectView):