Yes, I mean sash. How should I calculate the sash height to defer to a fixed relationship between the upper and lower sash? For example, in the top left corner of the lower sash I have it referring to the bottom left corner of the upper sash - what’s a better way to do this? 
I think part of my issue is stemming from the malleable LenZ middle components of the sides of the sashes, which are different heights due to the different sized counter weight cord grooves (which are different in real life - the top of is roughly 8 inches tall and the bottom one is just over 11 inches tall). I wanted to preserve the groove dimensions, so I built them into the corners, which have fixed dimensions.
What’s the workaround?