diff --git a/dlls/uiautomationcore/tests/uiautomation.c b/dlls/uiautomationcore/tests/uiautomation.c
index 13f481a670e..f7f16927b38 100644
--- a/dlls/uiautomationcore/tests/uiautomation.c
+++ b/dlls/uiautomationcore/tests/uiautomation.c
@@ -13952,11 +13952,11 @@ static void test_UiaAddEvent_client_proc(void)
     SET_EXPECT_MULTI(prov_callback_nonclient, 2);
     SET_EXPECT_MULTI(prov_callback_proxy, 3);
     hr = UiaEventAddWindow(event, hwnd);
-    todo_wine ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
-    todo_wine CHECK_CALLED(prov_callback_base_hwnd);
-    todo_wine CHECK_CALLED(prov_callback_nonclient);
+    ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
+    CHECK_CALLED(prov_callback_base_hwnd);
+    CHECK_CALLED(prov_callback_nonclient);
     todo_wine CHECK_CALLED(prov_callback_proxy);
-    post_event_message(hwnd, WM_UIA_TEST_CHECK_EVENT_ADVISE_ADDED, UIA_AutomationFocusChangedEventId, PROVIDER_ID, TRUE);
+    post_event_message(hwnd, WM_UIA_TEST_CHECK_EVENT_ADVISE_ADDED, UIA_AutomationFocusChangedEventId, PROVIDER_ID, FALSE);
 
     /* Successfully raise event. */
     GetWindowThreadProcessId(hwnd, &pid);
@@ -14000,7 +14000,7 @@ static void test_UiaAddEvent_client_proc(void)
 
     hr = UiaRemoveEvent(event);
     ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
-    post_event_message(hwnd, WM_UIA_TEST_CHECK_EVENT_ADVISE_REMOVED, UIA_AutomationFocusChangedEventId, PROVIDER_ID, TRUE);
+    post_event_message(hwnd, WM_UIA_TEST_CHECK_EVENT_ADVISE_REMOVED, UIA_AutomationFocusChangedEventId, PROVIDER_ID, FALSE);
 
     PostMessageW(hwnd, WM_UIA_TEST_RESET_EVENT_PROVIDERS, 0, 0);
     post_event_message(hwnd, WM_UIA_TEST_SET_EVENT_PROVIDER_DATA, HandleToUlong(hwnd), PROVIDER_ID,
@@ -14093,9 +14093,9 @@ static void test_UiaAddEvent_client_proc(void)
     SET_EXPECT_MULTI(prov_callback_nonclient, 2);
     SET_EXPECT_MULTI(prov_callback_proxy, 3);
     hr = UiaEventAddWindow(event, hwnd);
-    todo_wine ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
-    todo_wine CHECK_CALLED(prov_callback_base_hwnd);
-    todo_wine CHECK_CALLED(prov_callback_nonclient);
+    ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
+    CHECK_CALLED(prov_callback_base_hwnd);
+    CHECK_CALLED(prov_callback_nonclient);
     todo_wine CHECK_CALLED(prov_callback_proxy);
 
     /* Wrong runtime ID, no match. */
diff --git a/dlls/uiautomationcore/uia_classes.idl b/dlls/uiautomationcore/uia_classes.idl
index 651df86d9d2..25417d6c549 100644
--- a/dlls/uiautomationcore/uia_classes.idl
+++ b/dlls/uiautomationcore/uia_classes.idl
@@ -72,7 +72,7 @@ library UIA_wine_private
     ]
     interface IWineUiaEvent : IUnknown
     {
-        HRESULT advise_events([in]BOOL advise_added);
+        HRESULT advise_events([in]BOOL advise_added, [in]long adviser_start_idx);
         HRESULT set_event_data([in]const GUID *event_guid, [in]long scope, [in]VARIANT runtime_id,
                                [in]IWineUiaEvent *event_iface);
     }
diff --git a/dlls/uiautomationcore/uia_client.c b/dlls/uiautomationcore/uia_client.c
index 6d468b68705..e5cdec27e0b 100644
--- a/dlls/uiautomationcore/uia_client.c
+++ b/dlls/uiautomationcore/uia_client.c
@@ -544,6 +544,7 @@ static HRESULT WINAPI uia_node_attach_event(IWineUiaNode *iface, long proc_id, l
 {
     struct uia_node *node = impl_from_IWineUiaNode(iface);
     struct uia_event *event = NULL;
+    int old_event_advisers_count;
     HRESULT hr;
 
     TRACE("%p, %ld, %ld, %p\n", node, proc_id, event_cookie, ret_event);
@@ -557,6 +558,7 @@ static HRESULT WINAPI uia_node_attach_event(IWineUiaNode *iface, long proc_id, l
     if (hr == S_OK)
         *ret_event = &event->IWineUiaEvent_iface;
 
+    old_event_advisers_count = event->event_advisers_count;
     hr = attach_event_to_node_provider(iface, 0, (HUIAEVENT)event);
     if (FAILED(hr))
     {
@@ -575,6 +577,14 @@ static HRESULT WINAPI uia_node_attach_event(IWineUiaNode *iface, long proc_id, l
         event->u.serverside.node = iface;
     }
 
+    /*
+     * Pre-existing serverside event that has already had its initial
+     * advise call and gotten event data - if we've got new advisers, we need
+     * to advise them here.
+     */
+    if (!(*ret_event) && event->event_id && (event->event_advisers_count != old_event_advisers_count))
+        hr = IWineUiaEvent_advise_events(&event->IWineUiaEvent_iface, TRUE, old_event_advisers_count);
+
     return hr;
 }
 
@@ -3542,15 +3552,6 @@ exit:
     return hr;
 }
 
-/***********************************************************************
- *          UiaEventAddWindow (uiautomationcore.@)
- */
-HRESULT WINAPI UiaEventAddWindow(HUIAEVENT huiaevent, HWND hwnd)
-{
-    FIXME("(%p, %p): stub\n", huiaevent, hwnd);
-    return E_NOTIMPL;
-}
-
 /***********************************************************************
  *          UiaEventRemoveWindow (uiautomationcore.@)
  */
diff --git a/dlls/uiautomationcore/uia_event.c b/dlls/uiautomationcore/uia_event.c
index 2cb2cff9ae2..dd3578e7bd5 100644
--- a/dlls/uiautomationcore/uia_event.c
+++ b/dlls/uiautomationcore/uia_event.c
@@ -272,15 +272,15 @@ static ULONG WINAPI uia_event_Release(IWineUiaEvent *iface)
     return ref;
 }
 
-static HRESULT WINAPI uia_event_advise_events(IWineUiaEvent *iface, BOOL advise_added)
+static HRESULT WINAPI uia_event_advise_events(IWineUiaEvent *iface, BOOL advise_added, long adviser_start_idx)
 {
     struct uia_event *event = impl_from_IWineUiaEvent(iface);
     HRESULT hr;
     int i;
 
-    TRACE("%p, %d\n", event, advise_added);
+    TRACE("%p, %d, %ld\n", event, advise_added, adviser_start_idx);
 
-    for (i = 0; i < event->event_advisers_count; i++)
+    for (i = adviser_start_idx; i < event->event_advisers_count; i++)
     {
         hr = IWineUiaEventAdviser_advise(event->event_advisers[i], advise_added, (UINT_PTR)event);
         if (FAILED(hr))
@@ -658,7 +658,7 @@ static HRESULT WINAPI uia_serverside_event_adviser_advise(IWineUiaEventAdviser *
         }
     }
 
-    return IWineUiaEvent_advise_events(adv_events->event_iface, advise_added);
+    return IWineUiaEvent_advise_events(adv_events->event_iface, advise_added, 0);
 }
 
 static const IWineUiaEventAdviserVtbl uia_serverside_event_adviser_vtbl = {
@@ -706,6 +706,65 @@ HRESULT uia_event_add_serverside_event_adviser(IWineUiaEvent *serverside_event,
     return hr;
 }
 
+static HRESULT uia_event_advise(struct uia_event *event, BOOL advise_added, long start_idx)
+{
+    IWineUiaEvent *event_iface;
+    HRESULT hr;
+
+    if (event->u.clientside.git_cookie)
+    {
+        hr = get_interface_in_git(&IID_IWineUiaEvent, event->u.clientside.git_cookie,
+                (IUnknown **)&event_iface);
+        if (FAILED(hr))
+            return hr;
+    }
+    else
+    {
+        event_iface = &event->IWineUiaEvent_iface;
+        IWineUiaEvent_AddRef(event_iface);
+    }
+
+    hr = IWineUiaEvent_advise_events(event_iface, advise_added, start_idx);
+    IWineUiaEvent_Release(event_iface);
+
+    return hr;
+}
+
+/***********************************************************************
+ *          UiaEventAddWindow (uiautomationcore.@)
+ */
+HRESULT WINAPI UiaEventAddWindow(HUIAEVENT huiaevent, HWND hwnd)
+{
+    struct uia_event *event = unsafe_impl_from_IWineUiaEvent((IWineUiaEvent *)huiaevent);
+    int old_event_advisers_count;
+    HUIANODE node;
+    HRESULT hr;
+
+    TRACE("(%p, %p)\n", huiaevent, hwnd);
+
+    if (!event)
+        return E_INVALIDARG;
+
+    assert(event->event_type == EVENT_TYPE_CLIENTSIDE);
+
+    hr = UiaNodeFromHandle(hwnd, &node);
+    if (FAILED(hr))
+        return hr;
+
+    old_event_advisers_count = event->event_advisers_count;
+    hr = attach_event_to_uia_node(node, event);
+    if (FAILED(hr))
+        goto exit;
+
+    if (event->event_advisers_count != old_event_advisers_count)
+        hr = uia_event_advise(event, TRUE, old_event_advisers_count);
+
+exit:
+    UiaNodeRelease(node);
+
+    return hr;
+}
+
 /***********************************************************************
  *          UiaAddEvent (uiautomationcore.@)
  */
@@ -752,7 +811,7 @@ HRESULT WINAPI UiaAddEvent(HUIANODE huianode, EVENTID event_id, UiaEventCallback
     if (FAILED(hr))
         goto exit;
 
-    hr = IWineUiaEvent_advise_events(&event->IWineUiaEvent_iface, TRUE);
+    hr = uia_event_advise(event, TRUE, 0);
     if (FAILED(hr))
         goto exit;
 
@@ -775,7 +834,6 @@ exit:
 HRESULT WINAPI UiaRemoveEvent(HUIAEVENT huiaevent)
 {
     struct uia_event *event = unsafe_impl_from_IWineUiaEvent((IWineUiaEvent *)huiaevent);
-    IWineUiaEvent *event_iface;
     HRESULT hr;
 
     TRACE("(%p)\n", event);
@@ -784,33 +842,18 @@ HRESULT WINAPI UiaRemoveEvent(HUIAEVENT huiaevent)
         return E_INVALIDARG;
 
     assert(event->event_type == EVENT_TYPE_CLIENTSIDE);
+    hr = uia_event_advise(event, FALSE, 0);
+    if (FAILED(hr))
+        return hr;
+
     if (event->u.clientside.git_cookie)
     {
-        hr = get_interface_in_git(&IID_IWineUiaEvent, event->u.clientside.git_cookie, (IUnknown **)&event_iface);
-        if (FAILED(hr))
-            return hr;
-
         hr = unregister_interface_in_git(event->u.clientside.git_cookie);
         if (FAILED(hr))
-        {
-            IWineUiaEvent_Release(event_iface);
             return hr;
-        }
-
-        /*
-         * We want the release of the event_iface proxy to set the reference
-         * count to 0, so we release our reference here.
-         */
-        IWineUiaEvent_Release(&event->IWineUiaEvent_iface);
     }
-    else
-        event_iface = &event->IWineUiaEvent_iface;
-
-    hr = IWineUiaEvent_advise_events(event_iface, FALSE);
-    IWineUiaEvent_Release(event_iface);
-    if (FAILED(hr))
-        WARN("advise_events failed with hr %#lx\n", hr);
 
+    IWineUiaEvent_Release(&event->IWineUiaEvent_iface);
     return S_OK;
 }