diff --git a/Changes.md b/Changes.md
index 56480dd77d5..4bf78f08496 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,3 +1,11 @@
+1.1.9.x (relative to 1.1.9.1)
+=======
+
+Fixes
+-----
+
+- Tweak nodes : Fixed bugs which prevented the creation of new tweaks when an existing tweak had an input connection.
+
 1.1.9.1 (relative to 1.1.9.0)
 =======
 
diff --git a/python/GafferSceneUI/AttributeTweaksUI.py b/python/GafferSceneUI/AttributeTweaksUI.py
index 9ed9dcb3774..fe4cfd43d10 100644
--- a/python/GafferSceneUI/AttributeTweaksUI.py
+++ b/python/GafferSceneUI/AttributeTweaksUI.py
@@ -183,7 +183,10 @@ def __init__( self, plug ) :
 
 	def _updateFromPlug( self ) :
 
-		self.__button.setEnabled( self._editable() )
+		# Not using `_editable()` as it considers the whole plug to be non-editable if
+		# any child has an input connection, but that shouldn't prevent us adding a new
+		# tweak.
+		self.__button.setEnabled( self.getPlug().getInput() is None and not Gaffer.MetadataAlgo.readOnly( self.getPlug() ) )
 
 	def __menuDefinition( self ) :
 
diff --git a/python/GafferSceneUI/CameraTweaksUI.py b/python/GafferSceneUI/CameraTweaksUI.py
index 26c8d479abf..1cb0a63b5a2 100644
--- a/python/GafferSceneUI/CameraTweaksUI.py
+++ b/python/GafferSceneUI/CameraTweaksUI.py
@@ -184,7 +184,10 @@ def __init__( self, plug ) :
 
 	def _updateFromPlug( self ) :
 
-		self.__button.setEnabled( self._editable() )
+		# Not using `_editable()` as it considers the whole plug to be non-editable if
+		# any child has an input connection, but that shouldn't prevent us adding a new
+		# tweak.
+		self.__button.setEnabled( self.getPlug().getInput() is None and not Gaffer.MetadataAlgo.readOnly( self.getPlug() ) )
 
 	def __menuDefinition( self ) :
 
diff --git a/python/GafferSceneUI/OptionTweaksUI.py b/python/GafferSceneUI/OptionTweaksUI.py
index 6921b447dc5..f9e47da6b91 100644
--- a/python/GafferSceneUI/OptionTweaksUI.py
+++ b/python/GafferSceneUI/OptionTweaksUI.py
@@ -143,7 +143,10 @@ def __init__( self, plug ) :
 
 	def _updateFromPlug( self ) :
 
-		self.__button.setEnabled( self._editable() )
+		# Not using `_editable()` as it considers the whole plug to be non-editable if
+		# any child has an input connection, but that shouldn't prevent us adding a new
+		# tweak.
+		self.__button.setEnabled( self.getPlug().getInput() is None and not Gaffer.MetadataAlgo.readOnly( self.getPlug() ) )
 
 	def __menuDefinition( self ) :
 
diff --git a/python/GafferSceneUI/ShaderTweaksUI.py b/python/GafferSceneUI/ShaderTweaksUI.py
index 6e1c412d44d..78d8d8efd05 100644
--- a/python/GafferSceneUI/ShaderTweaksUI.py
+++ b/python/GafferSceneUI/ShaderTweaksUI.py
@@ -234,7 +234,10 @@ def __init__( self, plug ) :
 
 	def _updateFromPlug( self ) :
 
-		self.__button.setEnabled( self._editable() )
+		# Not using `_editable()` as it considers the whole plug to be non-editable if
+		# any child has an input connection, but that shouldn't prevent us adding a new
+		# tweak.
+		self.__button.setEnabled( self.getPlug().getInput() is None and not Gaffer.MetadataAlgo.readOnly( self.getPlug() ) )
 
 	def __menuDefinition( self ) :
 
diff --git a/python/GafferUI/ContextVariableTweaksUI.py b/python/GafferUI/ContextVariableTweaksUI.py
index e2d78057329..0360316f0b7 100644
--- a/python/GafferUI/ContextVariableTweaksUI.py
+++ b/python/GafferUI/ContextVariableTweaksUI.py
@@ -121,7 +121,10 @@ def __init__( self, plug ) :
 
 	def _updateFromPlug( self ) :
 
-		self.__button.setEnabled( self._editable() )
+		# Not using `_editable()` as it considers the whole plug to be non-editable if
+		# any child has an input connection, but that shouldn't prevent us adding a new
+		# tweak.
+		self.__button.setEnabled( self.getPlug().getInput() is None and not Gaffer.MetadataAlgo.readOnly( self.getPlug() ) )
 
 	def __menuDefinition( self ) :