diff --git a/src/ytdl_sub/config/validators/variable_validation.py b/src/ytdl_sub/config/validators/variable_validation.py
index a9b367d4..32a7fcbe 100644
--- a/src/ytdl_sub/config/validators/variable_validation.py
+++ b/src/ytdl_sub/config/validators/variable_validation.py
@@ -2,6 +2,7 @@ import copy
 from typing import List
 from typing import Optional
 from typing import Set
+from typing import Tuple
 
 from ytdl_sub.config.overrides import Overrides
 from ytdl_sub.config.plugin.plugin_mapping import PluginMapping
@@ -12,15 +13,16 @@ from ytdl_sub.config.validators.options import OptionsValidator
 from ytdl_sub.downloaders.url.validators import MultiUrlValidator
 from ytdl_sub.entries.script.variable_scripts import VARIABLE_SCRIPTS
 from ytdl_sub.script.script import Script
-from ytdl_sub.utils.exceptions import ValidationException
 from ytdl_sub.utils.script import ScriptUtils
 from ytdl_sub.validators.string_formatter_validators import validate_formatters
 
 
-def _get_added_variables(
+def _get_added_and_modified_variables(
     plugins: PresetPlugins, downloader_options: MultiUrlValidator, resolved_variables: Set[str]
-) -> Set[str]:
+) -> Tuple[Set[str], Set[str]]:
     added_variables: Set[str] = set()
+    modified_variables: Set[str] = set()
+
     options: List[OptionsValidator] = plugins.plugin_options
     options.append(downloader_options)
 
@@ -31,7 +33,10 @@ def _get_added_variables(
         ).values():
             added_variables |= set(plugin_added_variables)
 
-    return added_variables
+        for plugin_modified_variables in plugin_options.modified_variables().values():
+            modified_variables |= plugin_modified_variables
+
+    return added_variables, modified_variables
 
 
 def _override_variables(overrides: Overrides) -> Set[str]:
@@ -59,19 +64,25 @@ class VariableValidation:
 
     def initialize_overrides(self, overrides: Overrides) -> "VariableValidation":
         entry_variables = _entry_variables()
-        self.resolved_variables = entry_variables.union(_override_variables(overrides))
+        override_variables = _override_variables(overrides)
 
-        # Set unresolved as variables that are added but do not exist as entry/override variables
-        self.unresolved_variables = (
-            _get_added_variables(
-                plugins=self.plugins,
-                downloader_options=self.downloader_options,
-                resolved_variables=self.resolved_variables,
-            )
-            - self.resolved_variables
+        # Set resolved variables as all entry + override variables
+        # at this point to generate every possible added/modified variable
+        self.resolved_variables = entry_variables | override_variables
+        added_variables, modified_variables = _get_added_and_modified_variables(
+            plugins=self.plugins,
+            downloader_options=self.downloader_options,
+            resolved_variables=self.resolved_variables,
         )
 
-        # Initialize overrides with unresolved variables to throw an error
+        # Set unresolved as variables that are added but do not exist as entry/override variables
+        # Then update resolved variables to reflect that
+        self.unresolved_variables = added_variables | modified_variables
+        self.resolved_variables -= self.unresolved_variables
+
+        # Initialize overrides with unresolved variables + modified variables to throw an error.
+        # For modified variables, this is to prevent a resolve(update=True) to setting any
+        # dependencies until it has been explicitly added
         overrides = overrides.initialize_script(
             unresolved_variables={
                 var_name: f"{{%throw('Plugin variable {var_name} has not been created yet')}}"
@@ -94,17 +105,20 @@ class VariableValidation:
             resolved_variables=self.resolved_variables,
             unresolved_variables=self.unresolved_variables,
         ).get(plugin_op, set())
+        modified_variables = options.modified_variables().get(plugin_op, set())
 
         if added_variables:
             for added_variable in added_variables:
                 if added_variable in self.resolved_variables:
-                    raise ValidationException(
+                    raise options._validation_exception(
                         f"Tried added the variable '{added_variable}', but it already "
                         f"exists as a defined variable."
                     )
 
-            self.script.add(ScriptUtils.add_dummy_variables(added_variables))
-            self.unresolved_variables -= added_variables
+        resolved_variables = added_variables | modified_variables
+
+        self.script.add(ScriptUtils.add_dummy_variables(resolved_variables))
+        self.unresolved_variables -= resolved_variables
 
         return added_variables
 
diff --git a/src/ytdl_sub/plugins/regex.py b/src/ytdl_sub/plugins/regex.py
index cf21eab5..af450406 100644
--- a/src/ytdl_sub/plugins/regex.py
+++ b/src/ytdl_sub/plugins/regex.py
@@ -260,6 +260,12 @@ class RegexOptions(OptionsDictValidator):
             ):
                 key = PluginOperation.MODIFY_ENTRY_METADATA
 
+            for capture_group_name in regex_options.capture_group_names:
+                if capture_group_name in resolved_variables:
+                    raise self._validation_exception(
+                        f"cannot use '{capture_group_name}' as a capture group name because it is "
+                        f"a defined variable"
+                    )
             added_source_vars[key] |= set(regex_options.capture_group_names)
 
         return added_source_vars
diff --git a/tests/e2e/plugins/test_regex.py b/tests/e2e/plugins/test_regex.py
index c61dad73..c0d824e5 100644
--- a/tests/e2e/plugins/test_regex.py
+++ b/tests/e2e/plugins/test_regex.py
@@ -313,7 +313,7 @@ class TestRegex:
         with pytest.raises(
             ValidationException,
             match=re.escape(
-                "Tried added the variable 'uid', but it already exists as a defined variable"
+                "cannot use 'uid' as a capture group name because it is a defined variable"
             ),
         ):
             _ = Subscription.from_dict(
@@ -333,8 +333,8 @@ class TestRegex:
         with pytest.raises(
             ValidationException,
             match=re.escape(
-                "Tried added the variable 'contains_regex_default', but it already exists "
-                "as a defined variable"
+                "cannot use 'contains_regex_default' as a capture group name because it is a "
+                "defined variable"
             ),
         ):
             _ = Subscription.from_dict(