diff --git a/generic/forms.py b/generic/forms.py
index 20d81691..cf56377b 100755
--- a/generic/forms.py
+++ b/generic/forms.py
@@ -593,77 +593,112 @@ class UserUserGroupForm(ModelForm):
 
             url = reverse("generic:user_search_widget")
 
+            # Build a small grade filter select
+            grades_options = '<option value="">All grades</option>'
+            try:
+                from generic.models import UserGrades
+                grades_qs = UserGrades.objects.all()
+                for g in grades_qs:
+                    grades_options += f'<option value="{g.pk}">{g.name}</option>'
+            except Exception:
+                grades_options = '<option value="">All grades</option>'
+
             html = f"""
-<div class="user-search-widget">
-  <select name="{self.name}" id="{field_id}" multiple class="d-none">
-    {options_html}
-  </select>
+            <div class="user-search-widget">
+                <select name="{self.name}" id="{field_id}" multiple class="d-none">
+                    {options_html}
+                </select>
 
-  <div class="mb-2">
-    <input type="search" id="{search_id}" class="form-control form-control-sm" placeholder="Search users by name, username or email" />
-    <div id="{results_id}" class="mt-2"></div>
-  </div>
+                <div class="mb-2">
+                    <div class="d-flex gap-2">
+                        <input type="search" id="{search_id}" class="form-control form-control-sm" placeholder="Search users by name, username or email" />
+                        <select id="grade_filter_{self.name}" class="form-select form-select-sm" style="max-width:180px">
+                            {grades_options}
+                        </select>
+                    </div>
+                    <div id="{results_id}" class="mt-2"></div>
+                </div>
 
-  <div>
-    <label class="form-label small">Selected users</label>
-    <ul id="{selected_list_id}" class="list-group list-group-flush">
-      {selected_html}
-    </ul>
-  </div>
+                <div>
+                    <label class="form-label small">Selected users</label>
+                    <ul id="{selected_list_id}" class="list-group list-group-flush">
+                        {selected_html}
+                    </ul>
+                </div>
 
-  <script>
-    (function() {{
-      const search = document.getElementById('{search_id}');
-      const results = document.getElementById('{results_id}');
-      const select = document.getElementById('{field_id}');
-      const selectedList = document.getElementById('{selected_list_id}');
+                <script>
+                    (function() {{
+                        const search = document.getElementById('{search_id}');
+                        const results = document.getElementById('{results_id}');
+                        const select = document.getElementById('{field_id}');
+                        const selectedList = document.getElementById('{selected_list_id}');
+                        const gradeSelect = document.getElementById('grade_filter_{self.name}');
 
-      let timeout = null;
-      function fetchResults(q) {{
-        if (!q || q.trim().length === 0) {{
-          results.innerHTML = '';
-          return;
-        }}
-        fetch('{url}?field=' + encodeURIComponent('{self.name}') + '&q=' + encodeURIComponent(q))
-          .then(r => r.text())
-          .then(html => {{ results.innerHTML = html; }});
-      }}
+                        let timeout = null;
+                        function fetchResults(q) {{
+                            const grade = gradeSelect ? gradeSelect.value : '';
+                            if (!q || q.trim().length === 0) {{
+                                results.innerHTML = '';
+                                return;
+                            }}
+                            const url = '{url}?field=' + encodeURIComponent('{self.name}') + '&q=' + encodeURIComponent(q) + (grade ? '&grade=' + encodeURIComponent(grade) : '');
+                            fetch(url)
+                                .then(r => r.text())
+                                .then(html => {{ results.innerHTML = html; }});
+                        }}
 
-      search.addEventListener('keyup', function(e) {{
-        clearTimeout(timeout);
-        timeout = setTimeout(() => fetchResults(search.value), 300);
-      }});
+                        search.addEventListener('keyup', function(e) {{
+                            clearTimeout(timeout);
+                            timeout = setTimeout(() => fetchResults(search.value), 300);
+                        }});
 
-      window.addUserToField = function(fieldName, id, text) {{
-        const sel = document.getElementById('id_' + fieldName);
-        if (!sel) return;
-        // prevent duplicate
-        for (let i=0;i<sel.options.length;i++) {{ if (sel.options[i].value == id) return; }}
-        const opt = document.createElement('option'); opt.value = id; opt.selected = true; opt.text = text;
-        sel.appendChild(opt);
+                        gradeSelect && gradeSelect.addEventListener('change', function(e) {{
+                            // re-run search with same query when grade changes
+                            clearTimeout(timeout);
+                            timeout = setTimeout(() => fetchResults(search.value), 50);
+                        }});
 
-        // add to visible list
-        const li = document.createElement('li');
-        li.className = 'list-group-item d-flex justify-content-between align-items-center';
-        li.id = 'selected_user_' + fieldName + '_' + id;
-        const span = document.createElement('span'); span.innerHTML = text;
-        const btn = document.createElement('button'); btn.type = 'button'; btn.className = 'btn btn-sm btn-outline-danger ms-2'; btn.innerText = 'Remove';
-        btn.addEventListener('click', function() {{ removeUserFromField(fieldName, id); }});
-        li.appendChild(span); li.appendChild(btn);
-        selectedList.appendChild(li);
-      }}
+                        window.addUserToField = function(fieldName, id, text) {{
+                            const sel = document.getElementById('id_' + fieldName);
+                            if (!sel) return;
+                            // prevent duplicate
+                            for (let i=0;i<sel.options.length;i++) {{ if (sel.options[i].value == id) return; }}
+                            const opt = document.createElement('option'); opt.value = id; opt.selected = true; opt.text = text;
+                            sel.appendChild(opt);
 
-      window.removeUserFromField = function(fieldName, id) {{
-        const sel = document.getElementById('id_' + fieldName);
-        if (!sel) return;
-        for (let i=sel.options.length-1;i>=0;i--) {{ if (sel.options[i].value == id) sel.remove(i); }}
-        const li = document.getElementById('selected_user_' + fieldName + '_' + id);
-        if (li && li.parentNode) li.parentNode.removeChild(li);
-      }}
-    }})();
-  </script>
-</div>
-"""
+                            // add to visible list
+                            const li = document.createElement('li');
+                            li.className = 'list-group-item d-flex justify-content-between align-items-center';
+                            li.id = 'selected_user_' + fieldName + '_' + id;
+                            const span = document.createElement('span'); span.innerHTML = text;
+                            const btn = document.createElement('button'); btn.type = 'button'; btn.className = 'btn btn-sm btn-outline-danger ms-2'; btn.innerText = 'Remove';
+                            btn.addEventListener('click', function() {{ removeUserFromField(fieldName, id); }});
+                            li.appendChild(span); li.appendChild(btn);
+                            selectedList.appendChild(li);
+                        }}
+
+                        window.removeUserFromField = function(fieldName, id) {{
+                            const sel = document.getElementById('id_' + fieldName);
+                            if (!sel) return;
+                            for (let i=sel.options.length-1;i>=0;i--) {{ if (sel.options[i].value == id) sel.remove(i); }}
+                            const li = document.getElementById('selected_user_' + fieldName + '_' + id);
+                            if (li && li.parentNode) li.parentNode.removeChild(li);
+                        }}
+
+                        window.addAllFromResults = function(fieldName) {{
+                            const list = document.getElementById('user_search_results_list_' + fieldName);
+                            if (!list) return;
+                            const items = list.querySelectorAll('li[data-user-id]');
+                            items.forEach(function(it) {{
+                                const id = it.getAttribute('data-user-id');
+                                const text = it.getAttribute('data-user-text') || it.textContent.trim();
+                                addUserToField(fieldName, id, text);
+                            }});
+                        }}
+                    }})();
+                </script>
+            </div>
+            """
 
             return mark_safe(html)
 
diff --git a/generic/models.py b/generic/models.py
index c69d8740..c3a15775 100644
--- a/generic/models.py
+++ b/generic/models.py
@@ -1967,6 +1967,13 @@ class ExamCollection(models.Model, AuthorMixin):
         if UserUserGroup is None:
             raise RuntimeError("UserUserGroup model not available")
 
+        # Debug: log what we received
+        try:
+            group_pks = [g.pk for g in groups] if groups is not None else []
+        except Exception:
+            group_pks = []
+        logger.debug("bulk_add_user_user_groups called on collection=%s with groups=%s exam_types=%s", self.pk, group_pks, exam_types)
+
         # Normalize groups to a list of model instances
         if groups is None:
             return 0
@@ -1994,9 +2001,21 @@ class ExamCollection(models.Model, AuthorMixin):
             for exam in exams:
                 # Each exam model exposes a `user_user_groups` ManyToManyField
                 try:
+                    before_pks = set(exam.user_user_groups.values_list('pk', flat=True))
                     exam.user_user_groups.add(*groups_qs)
                     # Ensure any downstream signals / caches see the change
                     exam.save()
+                    after_pks = set(exam.user_user_groups.values_list('pk', flat=True))
+                    # log if expected group pks are not present after add
+                    try:
+                        expected_pks = {g.pk for g in groups_qs}
+                    except Exception:
+                        expected_pks = set()
+                    if not expected_pks.issubset(after_pks):
+                        logger.warning(
+                            "After add, exam %s missing expected user_user_groups; before=%s after=%s expected=%s",
+                            getattr(exam, 'pk', exam), sorted(before_pks), sorted(after_pks), sorted(expected_pks),
+                        )
                     updated += 1
                 except Exception as e:
                     logger.exception("Failed to add user_user_groups to exam %s: %s", getattr(exam, 'pk', exam), e)
@@ -2011,6 +2030,13 @@ class ExamCollection(models.Model, AuthorMixin):
         if CidUserGroup is None:
             raise RuntimeError("CidUserGroup model not available")
 
+        # Debug: log what we received
+        try:
+            group_pks = [g.pk for g in groups] if groups is not None else []
+        except Exception:
+            group_pks = []
+        logger.debug("bulk_add_cid_user_groups called on collection=%s with groups=%s exam_types=%s", self.pk, group_pks, exam_types)
+
         if groups is None:
             return 0
 
@@ -2033,8 +2059,19 @@ class ExamCollection(models.Model, AuthorMixin):
             for exam in exams:
                 # Each exam model exposes a `cid_user_groups` ManyToManyField
                 try:
+                    before_pks = set(exam.cid_user_groups.values_list('pk', flat=True))
                     exam.cid_user_groups.add(*groups_qs)
                     exam.save()
+                    after_pks = set(exam.cid_user_groups.values_list('pk', flat=True))
+                    try:
+                        expected_pks = {g.pk for g in groups_qs}
+                    except Exception:
+                        expected_pks = set()
+                    if not expected_pks.issubset(after_pks):
+                        logger.warning(
+                            "After add, exam %s missing expected cid_user_groups; before=%s after=%s expected=%s",
+                            getattr(exam, 'pk', exam), sorted(before_pks), sorted(after_pks), sorted(expected_pks),
+                        )
                     updated += 1
                 except Exception as e:
                     logger.exception("Failed to add cid_user_groups to exam %s: %s", getattr(exam, 'pk', exam), e)
diff --git a/generic/templates/generic/partials/user_search_widget_results.html b/generic/templates/generic/partials/user_search_widget_results.html
index 5ea7b4d3..62ba7527 100644
--- a/generic/templates/generic/partials/user_search_widget_results.html
+++ b/generic/templates/generic/partials/user_search_widget_results.html
@@ -1,7 +1,7 @@
 {% if results %}
-  <ul class="list-unstyled mb-0">
+  <ul class="list-unstyled mb-0" id="user_search_results_list_{{ field }}">
     {% for item in results %}
-      <li class="py-1 d-flex justify-content-between align-items-center">
+      <li class="py-1 d-flex justify-content-between align-items-center" data-user-id="{{ item.id }}" data-user-text="{{ item.text|escapejs }}">
         <div class="flex-grow-1">{{ item.text|escape }}</div>
         <div>
           <button type="button" class="btn btn-sm btn-primary" onclick="addUserToField('{{ field }}', {{ item.id }}, '{{ item.text|escapejs }}')">Add</button>
@@ -9,6 +9,11 @@
       </li>
     {% endfor %}
   </ul>
+  {% if results %}
+    <div class="mt-2 text-end">
+      <button type="button" class="btn btn-sm btn-outline-success" onclick="addAllFromResults('{{ field }}')">Add all results</button>
+    </div>
+  {% endif %}
 {% else %}
   <div><em>No users found</em></div>
 {% endif %}
diff --git a/generic/views.py b/generic/views.py
index 16b9745e..980ffbb3 100644
--- a/generic/views.py
+++ b/generic/views.py
@@ -408,6 +408,23 @@ def exam_collection_bulk_add_groups(request, collection_id):
     else:
         exam_types = None
 
+    # Debug: log what was submitted so we can trace why groups may not be applied
+    try:
+        cid_pks = [g.pk for g in cid_groups] if cid_groups is not None else []
+    except Exception:
+        cid_pks = []
+    try:
+        user_pks = [g.pk for g in user_groups] if user_groups is not None else []
+    except Exception:
+        user_pks = []
+    logger.debug(
+        "ExamCollection bulk-add POST: collection=%s cid_groups=%s user_groups=%s exam_types=%s",
+        collection.pk,
+        cid_pks,
+        user_pks,
+        exam_types,
+    )
+
     total_user = 0
     total_cid = 0
     try:
@@ -5930,7 +5947,17 @@ def user_search_widget(request):
         | Q(last_name__icontains=q)
         | Q(email__icontains=q)
         | Q(username__icontains=q)
-    ).order_by("last_name", "first_name")[:10]
+    )
+
+    # optional grade filter (UserProfile.grade FK)
+    grade = request.GET.get('grade')
+    if grade:
+        try:
+            users_qs = users_qs.filter(userprofile__grade_id=int(grade))
+        except Exception:
+            pass
+
+    users_qs = users_qs.order_by("last_name", "first_name")[:10]
 
     results = [{"id": u.pk, "text": f"{u.get_full_name() or u.username} - {u.email or ''}"} for u in users_qs]