Thanks Michael. I was originally trying to fillet that side, but it wouldn't take, so instead I *grabbed* the edge of the armrest, extended the front and back with tangent lines and then swept a perfect aligned 'cutter' -- or so I thought. Why wouldn't the cutter be aligned correctly, especially since it was generated from the originating curves and started from the Z direction?

I kinda hoped, as a last resort, the sweep along a path and boolean subtract would work instead of fillets. Guess I should rethink. Thanks for the tip on Construct > Curve > isect !! :-)