diff --git a/edc_data_manager/admin/data_query_admin.py b/edc_data_manager/admin/data_query_admin.py
index ebbb13d..424f40a 100644
--- a/edc_data_manager/admin/data_query_admin.py
+++ b/edc_data_manager/admin/data_query_admin.py
@@ -29,14 +29,14 @@
 from ..auth_objects import DATA_MANAGER
 from ..constants import CLOSED_WITH_ACTION
 from ..forms import DataQueryForm
-from ..modeladmin_mixins import DataManagerModelAdminMixin
+from ..modeladmin_mixins import DataManagerSiteModelAdminMixin
 from ..models import DataDictionary, DataQuery
 from .actions import toggle_dm_status
 
 
 @register(DataQuery, site=edc_data_manager_admin)
 class DataQueryAdmin(
-    DataManagerModelAdminMixin, ModelAdminSubjectDashboardMixin, SimpleHistoryAdmin
+    DataManagerSiteModelAdminMixin, ModelAdminSubjectDashboardMixin, SimpleHistoryAdmin
 ):
     status_column_template_name = (
         f"edc_data_manager/bootstrap{get_bootstrap_version()}/columns/status.html"
diff --git a/edc_data_manager/modeladmin_mixins.py b/edc_data_manager/modeladmin_mixins.py
index 737f13f..f834bf1 100644
--- a/edc_data_manager/modeladmin_mixins.py
+++ b/edc_data_manager/modeladmin_mixins.py
@@ -5,14 +5,19 @@
 from django.utils.html import format_html
 from django.utils.safestring import mark_safe
 
-from edc_data_manager.auth_objects import DATA_MANAGER_ROLE
+from .auth_objects import DATA_MANAGER_ROLE
 
 
-class DataManagerModelAdminMixin:
+class DataManagerSiteModelAdminMixin:
+    """Do not declare together with `SiteModelAdminMixin`"""
+
+    on_site_manager = "on_site"
+
     def get_queryset(self: ModelAdmin, request):
         """
-        Return a QuerySet of all model instances that can be edited by the
-        admin site. This is used by changelist_view.
+        Return a QuerySet of all model instances for multiple sites
+        that can be viewed/edited by the admin site. This is used
+        by changelist_view.
         """
         expanded_view_roles = getattr(
             settings, "EDC_DATA_MANAGER_EXPANDED_VIEW_ROLES", [DATA_MANAGER_ROLE]
@@ -27,7 +32,7 @@ def get_queryset(self: ModelAdmin, request):
         roles = [r.name for r in request.user.userprofile.roles.all()]
         if list(set(expanded_view_roles) & set(roles)):
             site_ids = [s.id for s in request.user.userprofile.sites.all()]
-            qs = self.model.objects.get_queryset().filter(site_id__in=site_ids)
+            qs = self.model._default_manager.get_queryset().filter(site_id__in=site_ids)
             storage = get_messages(request)
             if not [message for message in storage if message.message == my_message]:
                 self.message_user(
@@ -37,7 +42,8 @@ def get_queryset(self: ModelAdmin, request):
                     fail_silently=True,
                 )
         else:
-            qs = self.model._default_manager.get_queryset()
+            manager = self.on_site_manager or "_default_manager"
+            qs = getattr(self.model, manager).get_queryset()
         ordering = self.get_ordering(request)
         if ordering:
             qs = qs.order_by(*ordering)