I'm not sure that it is possible to do it using UI, but using API it is an easy job.

But this iLogic rule is just a sample HOW TO... You need to implement this functionality to addin and you must keep variable _userInputEvents persistent and you can improve the condition when the linearMenu should be updated.
Sub Main()
_userInputEvents = ThisApplication.CommandManager.UserInputEvents
AddHandler _userInputEvents.OnLinearMarkingMenu, AddressOf UserInputEvents_OnLinearMarkingMenu
End Sub
Private _userInputEvents As UserInputEvents
Private Sub UserInputEvents_OnLinearMarkingMenu(selectedEntities As ObjectsEnumerator,
selectionDevice As SelectionDeviceEnum,
linearMenu As CommandControls,
additionalInfo As NameValueMap)
Dim sketchGeneralDimensionCmd As String = "SketchGeneralDimensionCmd"
Dim sketchCurvatureConstraintCmd As String = "SketchCurvatureWrapperCmd"
If linearMenu.Item(linearMenu.Count).ControlDefinition.InternalName = sketchCurvatureConstraintCmd Then
linearMenu.AddButton(ThisApplication.CommandManager.ControlDefinitions(sketchGeneralDimensionCmd))
End If
End Sub