Keeping stencil scale
 

I'm new to Omnigraffle pro and am hoping to get this seemingly simple problem solved.
I need to create room diagrams for meeting rooms of a variety of sizes. I need to adjust the scale to fit rooms ranging from small meeting rooms to large ballrooms. I created some stencils of seating and staging elements. How can I get the stencils to scale to various document scale size. Its a real pain in the ars to have to rescale stencils all the time making stencils almost not even worth using. Am I missing something? I find it hard to believe this can't be done and if not are there recommendations for the program better suited to do what I want.
Thanks All

Did you set a scale when you created your stencil? If you did, then the stencil should auto-scale to fit the diagram scale.