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I would recommend creating a simple face-based component, or even an in-place component family. Create simple extrusion to represent the interior curtain geometry. Then apply the desired material to represent the curtain appearance for rendering. I would avoid over-modeling this type of element, in order to ensure model performance is not affected.
For additional family questions I would utilize the Revit Families Guide at the link below:
Revit Architecture 2010 Families Guide
Thank you,