diff --git a/edc_consent/migrations/0003_edcpermissions_locale_created_and_more.py b/edc_consent/migrations/0003_edcpermissions_locale_created_and_more.py
new file mode 100644
index 0000000..3da353e
--- /dev/null
+++ b/edc_consent/migrations/0003_edcpermissions_locale_created_and_more.py
@@ -0,0 +1,34 @@
+# Generated by Django 4.2.7 on 2023-12-01 14:47
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("edc_consent", "0002_alter_edcpermissions_device_created_and_more"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="edcpermissions",
+            name="locale_created",
+            field=models.CharField(
+                blank=True,
+                help_text="Auto-updated by Modeladmin",
+                max_length=10,
+                null=True,
+                verbose_name="Locale created",
+            ),
+        ),
+        migrations.AddField(
+            model_name="edcpermissions",
+            name="locale_modified",
+            field=models.CharField(
+                blank=True,
+                help_text="Auto-updated by Modeladmin",
+                max_length=10,
+                null=True,
+                verbose_name="Locale modified",
+            ),
+        ),
+    ]
diff --git a/edc_consent/migrations/0004_alter_edcpermissions_options_and_more.py b/edc_consent/migrations/0004_alter_edcpermissions_options_and_more.py
new file mode 100644
index 0000000..1377c6d
--- /dev/null
+++ b/edc_consent/migrations/0004_alter_edcpermissions_options_and_more.py
@@ -0,0 +1,41 @@
+# Generated by Django 4.2.7 on 2023-12-04 22:19
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("edc_consent", "0003_edcpermissions_locale_created_and_more"),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name="edcpermissions",
+            options={
+                "default_manager_name": "objects",
+                "default_permissions": (
+                    "add",
+                    "change",
+                    "delete",
+                    "view",
+                    "export",
+                    "import",
+                ),
+                "verbose_name": "Edc Permissions",
+                "verbose_name_plural": "Edc Permissions",
+            },
+        ),
+        migrations.AddIndex(
+            model_name="edcpermissions",
+            index=models.Index(
+                fields=["modified", "created"], name="edc_consent_modifie_851b6a_idx"
+            ),
+        ),
+        migrations.AddIndex(
+            model_name="edcpermissions",
+            index=models.Index(
+                fields=["user_modified", "user_created"],
+                name="edc_consent_user_mo_27c64b_idx",
+            ),
+        ),
+    ]
diff --git a/edc_consent/model_mixins/consent_model_mixin.py b/edc_consent/model_mixins/consent_model_mixin.py
index e6ee722..03313e7 100644
--- a/edc_consent/model_mixins/consent_model_mixin.py
+++ b/edc_consent/model_mixins/consent_model_mixin.py
@@ -1,7 +1,7 @@
 from uuid import uuid4
 
 from django.db import models
-from django.db.models import options
+from django.db.models import UniqueConstraint, options
 from django_crypto_fields.fields import EncryptedTextField
 from edc_constants.constants import OPEN
 from edc_data_manager.get_data_queries import get_data_queries
@@ -148,21 +148,26 @@ class Meta:
         verbose_name = "Subject Consent"
         verbose_name_plural = "Subject Consents"
         consent_group = DEFAULT_CONSENT_GROUP
-        get_latest_by = "consent_datetime"
-        unique_together = (
-            ("first_name", "dob", "initials", "version"),
-            ("subject_identifier", "version"),
-        )
-        ordering = ("created",)
-
-        indexes = [
-            models.Index(
+        constraints = [
+            UniqueConstraint(
+                fields=["first_name", "dob", "initials", "version"],
+                name="%(app_label)s_%(class)s_first_uniq",
+            ),
+            UniqueConstraint(
                 fields=[
                     "subject_identifier",
                     "first_name",
                     "dob",
                     "initials",
                     "version",
-                ]
-            )
+                ],
+                name="%(app_label)s_%(class)s_subject_uniq",
+            ),
+            UniqueConstraint(
+                fields=[
+                    "version",
+                    "subject_identifier",
+                ],
+                name="%(app_label)s_%(class)s_version_uniq",
+            ),
         ]
diff --git a/edc_consent/models/edc_permissions.py b/edc_consent/models/edc_permissions.py
index 8144613..c3f4c2d 100644
--- a/edc_consent/models/edc_permissions.py
+++ b/edc_consent/models/edc_permissions.py
@@ -5,5 +5,5 @@
 class EdcPermissions(EdcPermissionsModelMixin, BaseUuidModel):
     # see edc_auth for permissions attached to this model
 
-    class Meta(EdcPermissionsModelMixin.Meta):
-        pass
+    class Meta(EdcPermissionsModelMixin.Meta, BaseUuidModel.Meta):
+        indexes = BaseUuidModel.Meta.indexes