Even simpler:
Go ahead and make the subcomponents and hide the lines you don’t want to be visible, then constrain the SCALE tool (in DC Attributes). For the corners, allow NO scaling, for the other pieces, allow scaling only along their length.
No need for formulas!
Flash update! I’m wrong! Either that or something strange is going on!
I followed my own advice and constrained the scaling on the subcomponents, then tried to scale the main (enclosing) component. It scaled in any direction - and did introduce the (in this case) unwanted distortions.
Darn!