diff --git a/gallagher/cc/core.py b/gallagher/cc/core.py
index 4a0b588c..22a1b7ea 100644
--- a/gallagher/cc/core.py
+++ b/gallagher/cc/core.py
@@ -429,7 +429,7 @@ async def _get(
             try:
 
                 response = await _httpx_async.get(
-                    f'{url}',
+                    f'{url}', # required to turn pydantic object to str
                     headers=get_authorization_headers(),
                 )
 
@@ -470,7 +470,7 @@ async def _post(
             try:
 
                 response = await _httpx_async.post(
-                    f'{url}',
+                    f'{url}', # required to turn pydantic object to str
                     json=payload.dict() if payload else None,
                     headers=get_authorization_headers(),
                 )
diff --git a/gallagher/dto/detail/access_group.py b/gallagher/dto/detail/access_group.py
index ab345639..f85f31bb 100644
--- a/gallagher/dto/detail/access_group.py
+++ b/gallagher/dto/detail/access_group.py
@@ -3,7 +3,8 @@
 from ..utils import (
     AppBaseModel,
     IdentityMixin,
-    HrefMixin
+    HrefMixin,
+    OptionalHrefMixin,
 )
 from ..summary import (
     AlarmSummary,
@@ -30,13 +31,13 @@ class AccessGroupDetail(
     description: Optional[str]
     parent: Optional[AccessGroupRef]
     division: IdentityMixin
-    cardholders: Optional[HrefMixin]
+    cardholders: OptionalHrefMixin
     server_display_name: Optional[str]
 
     description: Optional[str]
     parent: Optional[AccessGroupRef]
     division: DivisionDetail
-    cardholders: Optional[HrefMixin]
+    cardholders: OptionalHrefMixin
     server_display_name: Optional[str]
     children: list[AccessGroupRef]
     personal_data_definitions: list[PDFRef]
diff --git a/gallagher/dto/detail/alarm.py b/gallagher/dto/detail/alarm.py
index 2907bb29..6cf19dda 100644
--- a/gallagher/dto/detail/alarm.py
+++ b/gallagher/dto/detail/alarm.py
@@ -9,6 +9,7 @@
 from ..utils import (
     AppBaseModel,
     HrefMixin,
+    OptionalHrefMixin,
     IdentityMixin,
 )
 
@@ -56,18 +57,18 @@ class AlarmDetail(
     state: str
     active: bool
     division: HrefMixin
-    event: Optional[HrefMixin] = None
+    event: OptionalHrefMixin = None
     note_presets: list[str] = []
 
     # The following URLS should be used to follow through
     # on various actions that the system allows
     view: HrefMixin
     comment: HrefMixin
-    acknowledge: Optional[HrefMixin] = None
-    acknowledge_with_comment: Optional[HrefMixin] = None
-    process: Optional[HrefMixin] = None
-    process_with_comment: Optional[HrefMixin] = None
-    force_process: Optional[HrefMixin] = None
+    acknowledge: OptionalHrefMixin = None
+    acknowledge_with_comment: OptionalHrefMixin = None
+    process: OptionalHrefMixin = None
+    process_with_comment: OptionalHrefMixin = None
+    force_process: OptionalHrefMixin = None
 
     # Details fields, these are what don't appear in the summary
     details: Optional[str] = ""
diff --git a/gallagher/dto/detail/division.py b/gallagher/dto/detail/division.py
index 9ed50edd..5cfd4684 100644
--- a/gallagher/dto/detail/division.py
+++ b/gallagher/dto/detail/division.py
@@ -3,7 +3,8 @@
 from ..utils import (
     AppBaseModel,
     IdentityMixin,
-    HrefMixin
+    HrefMixin,
+    OptionalHrefMixin,
 )
 
 
@@ -18,7 +19,7 @@ class DivisionDetail(
     name: str
     description: Optional[str] = None
     server_display_name: Optional[str] = None
-    parent: Optional[HrefMixin] = None
+    parent: OptionalHrefMixin = None
 
     # TODO: Looks like we don't have access to visitor management
     # on our test instance at the moment
diff --git a/gallagher/dto/summary/access_group.py b/gallagher/dto/summary/access_group.py
index 004c6e32..8755f768 100644
--- a/gallagher/dto/summary/access_group.py
+++ b/gallagher/dto/summary/access_group.py
@@ -3,7 +3,8 @@
 from ..utils import (
     AppBaseModel,
     IdentityMixin,
-    HrefMixin
+    HrefMixin,
+    OptionalHrefMixin,
 )
 
 from ..ref import (
@@ -36,5 +37,5 @@ class AccessGroupSummary(
     description: Optional[str]
     parent: Optional[AccessGroupRef]
     division: IdentityMixin
-    cardholders: Optional[HrefMixin]
+    cardholders: OptionalHrefMixin
     server_display_name: Optional[str]
diff --git a/gallagher/dto/summary/alarm.py b/gallagher/dto/summary/alarm.py
index 7adf64e4..bb94640c 100644
--- a/gallagher/dto/summary/alarm.py
+++ b/gallagher/dto/summary/alarm.py
@@ -4,6 +4,7 @@
 from ..utils import (
     AppBaseModel,
     HrefMixin,
+    OptionalHrefMixin,
     IdentityMixin,
 )
 
@@ -45,15 +46,15 @@ class AlarmSummary(
     state: str
     active: bool
     division: HrefMixin
-    event: Optional[HrefMixin] = None
+    event: OptionalHrefMixin = None
     note_presets: list[str] = []
 
     # The following URLS should be used to follow through
     # on various actions that the system allows
     view: HrefMixin
     comment: HrefMixin
-    acknowledge: Optional[HrefMixin] = None
-    acknowledge_with_comment: Optional[HrefMixin] = None
-    process: Optional[HrefMixin] = None
-    process_with_comment: Optional[HrefMixin] = None
-    force_process: Optional[HrefMixin] = None
+    acknowledge: OptionalHrefMixin = None
+    acknowledge_with_comment: OptionalHrefMixin = None
+    process: OptionalHrefMixin = None
+    process_with_comment: OptionalHrefMixin = None
+    force_process: OptionalHrefMixin = None
diff --git a/gallagher/dto/summary/division.py b/gallagher/dto/summary/division.py
index 7f113095..c33cb7b2 100644
--- a/gallagher/dto/summary/division.py
+++ b/gallagher/dto/summary/division.py
@@ -6,7 +6,8 @@
 from ..utils import (
     AppBaseModel,
     IdentityMixin,
-    HrefMixin
+    HrefMixin,
+    OptionalHrefMixin,
 )
 
 
@@ -24,7 +25,7 @@ class DivisionSummary(
     name: str
     description: Optional[str] = None
     server_display_name: Optional[str] = None
-    parent: Optional[HrefMixin] = None
+    parent: OptionalHrefMixin = None
 
 
     def __rich_repr__(self):