How can styles be merged in Silverlight?

My goal is to extend the already set style of an object. So assuming I have the following two styles: ``` <Style TargetType="Ellipse" x:Key="OriginalStyle"> <Setter Property="Fill" Value="Blue"/> <Setter Property="Width" Value="100"/> <Setter Property="Height" Value="200"/> </Style> <Style TargetType="Ellipse" x:Key="NewStyle"> <Setter Property="Fill" Value="Red"/> </Style> ``` What I'd like to do is assign OriginalStyle to an Ellipse, then later apply the second style only changing the properties it affects. So ideally I want to do something like this: ``` Style OriginalStyle; Style NewStyle; Ellipse ellipse = new Ellipse(); ellipse .Style = OriginalStyle; // Later in an event hanler ellipse.Style = NewStyle; // I would want to keep the settings from the old style in here: in this example setting the style like this would make me lose the Width and Height properties! ``` I've tried to dynamically construct a new Style and add the properties of NewStyle and OldStyle - however the Property property of the styles are always null so this lead to a dead end: ``` Style combinedStyle = new Style(); foreach (Setter setter in Old.Setters) { combinedStyle.Setters.Add(setter); // Get exception "Element is already the child of another element." } foreach (Setter setter in NewStyle.Setters) { combinedStyle.Setters.Add(setter); // Get exception "Element is already the child of another element." } ``` It seems like there is no way to dynamically merge styles in Silverlight. Could someone confirm this or show me a better approach to achieve merging?