XDesign stretching imported .STEP files

Good Afternoon,

 

I am an old SW user, but don't use it much any more. I recently got the web-based XDESIGN system. My problem is this: I have a set of .STEP files with mitered frame components I'd like to stretch or otherwise modify (I.E., an end-fabricated frame with angled ends that I'd like to make 60" long when the original is X" long). Is there a way to modify my .STEP files? I can "move" the edges, but that doesn't really work since I want to stretch the frame along the long axis of the frame (not necessarily perpendicular to the edges of the frame).