How do you export from Expression Design to Silverlight XAML and keep vector relativity?

I am trying to export some pre-made assets from Expression Design 2 and into .XAML, with the final destination of Blend 2 for the layout, but I cannot find a reliable way to keep the ability to resize these assets when they reach Blend, Taking a look at the exported final product obtained The XAML is wrapped in a canvas (regardless of whether I choose this option in Export) with the Left / Top and Width / Height attributes hardcoded. This means that whatever size I exported becomes fixed and I can no longer control its size in Blend.

How do I export my assets and keep them dynamically volatile?