diff --git a/benchmark/benchmark.py b/benchmark/benchmark.py
index 7a1f6d223..3d9a2c091 100644
--- a/benchmark/benchmark.py
+++ b/benchmark/benchmark.py
@@ -149,3 +149,28 @@ def test_get_value_kind(
 
 def test_is_missing_literal(benchmark: Any) -> None:
     assert benchmark(_is_missing_literal, "???")
+
+
+@mark.parametrize("force_add", [False, True])
+def test_update_force_add(
+    large_dict_config: Any, force_add: bool, benchmark: Any
+) -> None:
+    if force_add:
+        OmegaConf.set_struct(large_dict_config, True)
+
+    def recursive_is_struct(node: Any) -> None:
+        if OmegaConf.is_config(node):
+            OmegaConf.is_struct(node)
+            for val in node.values():
+                recursive_is_struct(val)
+
+    recursive_is_struct(large_dict_config)
+
+    benchmark(
+        OmegaConf.update,
+        large_dict_config,
+        "a.a.a.a.a.a.a.a.a.a.a",
+        10,
+        merge=True,
+        force_add=force_add,
+    )
diff --git a/docs/source/usage.rst b/docs/source/usage.rst
index 16974f917..2b616c119 100644
--- a/docs/source/usage.rst
+++ b/docs/source/usage.rst
@@ -863,6 +863,7 @@ OmegaConf.update() allows you to update values in your config using either a dot
 
 The merge flag controls the behavior if the input is a dict or a list. If it's true, those are merged instead of
 being assigned.
+The force_add flag ensures that the path is created even if it will result in insertion of new values into struct nodes.
 
 .. doctest::
 
@@ -876,6 +877,10 @@ being assigned.
     >>> # Merge dictionary value (using bracket notation)
     >>> OmegaConf.update(cfg, "foo[bar]", {"oompa" : 40}, merge=True)
     >>> assert cfg.foo.bar == {"zonk" : 30, "oompa" : 40}
+    >>> # force_add ignores nodes in struct mode and updates anyway.
+    >>> OmegaConf.set_struct(cfg, True)
+    >>> OmegaConf.update(cfg, "a.b.c.d", 10, merge=True, force_add=True)
+    >>> assert cfg.a.b.c.d == 10
 
 
 
diff --git a/news/664.feature b/news/664.feature
new file mode 100644
index 000000000..6709f418b
--- /dev/null
+++ b/news/664.feature
@@ -0,0 +1 @@
+force_add flag added to OmegaConf.update(), ensuring that the path is created even if it will result in insertion of new values into struct nodes.
\ No newline at end of file
diff --git a/omegaconf/omegaconf.py b/omegaconf/omegaconf.py
index cc7714f3e..358c21311 100644
--- a/omegaconf/omegaconf.py
+++ b/omegaconf/omegaconf.py
@@ -727,7 +727,12 @@ def select(
 
     @staticmethod
     def update(
-        cfg: Container, key: str, value: Any = None, merge: Optional[bool] = None
+        cfg: Container,
+        key: str,
+        value: Any = None,
+        *,
+        merge: Optional[bool] = None,
+        force_add: bool = False,
     ) -> None:
         """
         Updates a dot separated key sequence to a value
@@ -739,7 +744,8 @@ def update(
         :param merge: If value is a dict or a list, True for merge, False for set.
             True to merge
             False to set
-            None (default) : deprecation warning and default to False
+            None (default): deprecation warning and default to False
+        :param force_add: insert the entire path regardless of Struct flag or Structured Config nodes.
         """
 
         if merge is None:
@@ -757,12 +763,14 @@ def update(
         split = split_key(key)
         root = cfg
         for i in range(len(split) - 1):
-            k = split[i]
-            # if next_root is a primitive (string, int etc) replace it with an empty map
-            next_root, key_ = _select_one(root, k, throw_on_missing=False)
-            if not isinstance(next_root, Container):
-                root[key_] = {}
-            root = root[key_]
+            struct_override = False if force_add else root._get_node_flag("struct")
+            with flag_override(root, "struct", struct_override):
+                k = split[i]
+                # if next_root is a primitive (string, int etc) replace it with an empty map
+                next_root, key_ = _select_one(root, k, throw_on_missing=False)
+                if not isinstance(next_root, Container):
+                    root[key_] = {}
+                root = root[key_]
 
         last = split[-1]
 
@@ -774,22 +782,24 @@ def update(
         if isinstance(root, ListConfig):
             last_key = int(last)
 
-        if merge and (OmegaConf.is_config(value) or is_primitive_container(value)):
-            assert isinstance(root, BaseContainer)
-            node = root._get_node(last_key)
-            if OmegaConf.is_config(node):
-                assert isinstance(node, BaseContainer)
-                node.merge_with(value)
-                return
-
-        if OmegaConf.is_dict(root):
-            assert isinstance(last_key, str)
-            root.__setattr__(last_key, value)
-        elif OmegaConf.is_list(root):
-            assert isinstance(last_key, int)
-            root.__setitem__(last_key, value)
-        else:
-            assert False
+        struct_override = False if force_add else root._get_node_flag("struct")
+        with flag_override(root, "struct", struct_override):
+            if merge and (OmegaConf.is_config(value) or is_primitive_container(value)):
+                assert isinstance(root, BaseContainer)
+                node = root._get_node(last_key)
+                if OmegaConf.is_config(node):
+                    assert isinstance(node, BaseContainer)
+                    node.merge_with(value)
+                    return
+
+            if OmegaConf.is_dict(root):
+                assert isinstance(last_key, str)
+                root.__setattr__(last_key, value)
+            elif OmegaConf.is_list(root):
+                assert isinstance(last_key, int)
+                root.__setitem__(last_key, value)
+            else:
+                assert False
 
     @staticmethod
     def to_yaml(cfg: Any, *, resolve: bool = False, sort_keys: bool = False) -> str:
diff --git a/tests/test_update.py b/tests/test_update.py
index b34c876c8..bf44782fb 100644
--- a/tests/test_update.py
+++ b/tests/test_update.py
@@ -6,7 +6,8 @@
 
 from omegaconf import ListConfig, OmegaConf, ValidationError
 from omegaconf._utils import _ensure_container, is_primitive_container
-from tests import Package
+from omegaconf.errors import ConfigAttributeError, ConfigKeyError
+from tests import Package, User
 
 
 @mark.parametrize(
@@ -195,3 +196,32 @@ def test_merge_deprecation() -> None:
     with warns(UserWarning, match=re.escape(msg)):
         OmegaConf.update(cfg, "a", {"c": 20})  # default to set, and issue a warning.
         assert cfg == {"a": {"c": 20}}
+
+
+@mark.parametrize(
+    "cfg,key,value,expected",
+    [
+        param({}, "a", 10, {"a": 10}, id="add_value"),
+        param({}, "a.b", 10, {"a": {"b": 10}}, id="add_value"),
+        param({}, "a", {"b": 10}, {"a": {"b": 10}}, id="add_dict"),
+        param({}, "a.b", {"c": 10}, {"a": {"b": {"c": 10}}}, id="add_dict"),
+        param({}, "a", [1, 2], {"a": [1, 2]}, id="add_list"),
+        param({}, "a.b", [1, 2], {"a": {"b": [1, 2]}}, id="add_list"),
+        param(
+            {"user": User(name="Bond", age=7)},
+            "user.location",
+            "London",
+            {"user": {"name": "Bond", "age": 7, "location": "London"}},
+            id="inserting_into_nested_structured_config",
+        ),
+    ],
+)
+def test_update_force_add(cfg: Any, key: str, value: Any, expected: Any) -> None:
+    cfg = _ensure_container(cfg)
+    OmegaConf.set_struct(cfg, True)
+
+    with raises((ConfigAttributeError, ConfigKeyError)):  # type: ignore
+        OmegaConf.update(cfg, key, value, merge=True, force_add=False)
+
+    OmegaConf.update(cfg, key, value, merge=True, force_add=True)
+    assert cfg == expected