diff --git a/docs/diagrams/bedrock_basket_ctms_acoustic.md b/docs/diagrams/bedrock_basket_ctms_acoustic.md
index 130713b0..c0f6cdb1 100644
--- a/docs/diagrams/bedrock_basket_ctms_acoustic.md
+++ b/docs/diagrams/bedrock_basket_ctms_acoustic.md
@@ -19,28 +19,28 @@ sequenceDiagram
     %% https://github.com/mozilla/bedrock/blob/ecba76406ed35c04d35532c3ed7562b09d65fabe/bedrock/products/views.py#L68-L87
 
     Basket->>Basket Task: Spawn task
-    %% https://github.com/mozmeao/basket/blob/77f98bb63c70cecbb3ec8d69b512df67abce8c63/basket/news/views.py#L681
+    %% https://github.com/mozmeao/basket/blob/2023-07-06/basket/news/views.py#L681
 
     Basket-->>Bedrock: [status]
     Bedrock-->>Visitor: .
 
     rect rgb(240,240,240)
     Basket Task->>Basket Task: Process data
-    %% https://github.com/mozmeao/basket/blob/77f98bb63c70cecbb3ec8d69b512df67abce8c63/basket/news/backends/ctms.py#L199
+    %% https://github.com/mozmeao/basket/blob/2023-07-06/basket/news/backends/ctms.py#L263
 
     Basket Task->>CTMS: update(token, email_id, newsletters, fpn_platform, fpn_country)
-    %% https://github.com/mozmeao/basket/blob/77f98bb63c70cecbb3ec8d69b512df67abce8c63/basket/news/tasks.py#L654
-    %% https://github.com/mozilla-it/ctms-api/blob/6f903aeb90b65c170f34485e1cc4b3755839daaf/ctms/crud.py#L563
+    %% https://github.com/mozmeao/basket/blob/2023-07-06/basket/news/tasks.py#L401
+    %% https://github.com/mozilla-it/ctms-api/blob/v2.1.0/ctms/crud.py#L579
 
     CTMS-->>Basket Task: .
     end
 
     rect rgb(240,240,240)
     CTMS Sync->>CTMS Sync: Flatten fields
-    %% https://github.com/mozilla-it/ctms-api/blob/cde9694e2992c2c9d8315ba9c6954c50a6facf37/ctms/acoustic_service.py#L62
+    %% https://github.com/mozilla-it/ctms-api/blob/v2.1.0/ctms/acoustic_service.py#L141
 
     CTMS Sync->>Acoustic: sync_records()
-    %% https://github.com/mozilla-it/ctms-api/blob/cde9694e2992c2c9d8315ba9c6954c50a6facf37/ctms/bin/acoustic_sync.py
+    %% https://github.com/mozilla-it/ctms-api/blob/v2.1.0/ctms/bin/acoustic_sync.py
     end
 ```
 
@@ -119,10 +119,17 @@ CTMS create contact ([`POST /ctms`](https://github.com/mozilla-it/ctms-api/blob/
             "lang": "fr",
         }
     ],
-    "vpn_waitlist": {
-        "geo": "fr",
-        "platform": "ios,mac",
-    },
+    "waitlist": [
+        {
+            "name": "vpn",
+            "subscribed": True,
+            "source": "https://vpn.mozilla.org/fr",
+            "fields": {
+                "geo": "fr",
+                "platform": "ios,mac"
+            }
+        }
+    ]
 }
 ```
 
diff --git a/tests/integration/test_basket_waitlist_subscription.py b/tests/integration/test_basket_waitlist_subscription.py
index 979e3ddc..a0bd834d 100644
--- a/tests/integration/test_basket_waitlist_subscription.py
+++ b/tests/integration/test_basket_waitlist_subscription.py
@@ -139,6 +139,7 @@ def fetch_created():
             "unsub_reason": None,
         }
     ]
+    # Legacy (read-only) fields.
     assert contact_details["vpn_waitlist"] == {
         "geo": "us",
         "platform": "ios,android",
@@ -150,17 +151,18 @@ def fetch_created():
         f"{settings.ctms_server_url}/ctms/{email_id}",
         headers=ctms_headers,
         json={
-            "vpn_waitlist": {"geo": "fr", "platform": "linux"},
+            "waitlists": [
+                {
+                    "name": "vpn",
+                    "fields": {"geo": "fr", "platform": "linux"},
+                }
+            ],
         },
     )
     resp.raise_for_status()
     # Request the full contact details again.
     contact_details = ctms_fetch(email, ctms_headers)
     assert contact_details["newsletters"] == []
-    assert contact_details["vpn_waitlist"] == {
-        "geo": "fr",
-        "platform": "linux",
-    }
     assert contact_details["waitlists"] == [
         {
             "name": "vpn",
@@ -173,6 +175,11 @@ def fetch_created():
             "unsub_reason": None,
         }
     ]
+    # Legacy (read-only) fields.
+    assert contact_details["vpn_waitlist"] == {
+        "geo": "fr",
+        "platform": "linux",
+    }
 
     # 4. Unsubscribe via Basket
     basket_token = contact_details["email"]["basket_token"]
@@ -185,6 +192,7 @@ def check_updated():
         contact_details = ctms_fetch(email, ctms_headers)
         assert contact_details["newsletters"] == []
         assert not contact_details["waitlists"][0]["subscribed"]
+        # Legacy (read-only) fields.
         assert contact_details["vpn_waitlist"] == {
             "geo": None,
             "platform": None,
@@ -225,6 +233,7 @@ def fetch_created():
             "unsub_reason": None,
         }
     ]
+    # Legacy (read-only) fields.
     assert contact_details["relay_waitlist"] == {
         "geo": "es",
     }
@@ -267,9 +276,9 @@ def check_subscribed():
             "unsub_reason": None,
         },
     ]
+    # Legacy (read-only) fields.
     # If multiple `relay-` waitlists are present, the `geo` field of the
-    # first waitlist is set as the value of `relay_waitlist["geo"]`. This
-    # property is intended for legacy consumers
+    # first waitlist is set as the value of `relay_waitlist["geo"]`.
     assert contact_details["relay_waitlist"] == {
         "geo": "es",
     }
@@ -307,6 +316,7 @@ def check_unsubscribed():
             "unsub_reason": None,
         },
     ]
+    # Legacy (read-only) fields.
     # relay_waitlist geo is pulled from the remaining waitlist.
     assert contact_details["relay_waitlist"] == {
         "geo": "fr",
@@ -325,5 +335,6 @@ def check_unsubscribed_last():
 
     contact_details = check_unsubscribed_last()
     assert contact_details["newsletters"] == []
+    # Legacy (read-only) fields.
     # Relay attribute is now empty
     assert contact_details["relay_waitlist"] == {"geo": None}