Add Nominal Transform Column to your Graph Builder with formula with just value 1 and rename if you want to


Add that new Nominal column as extra column to both X and Y Axis

Disable plot (and other) plots for those placeholder graphs and add distribution for those. You can do this by holding ctrl+shift and clicking different plot types from corners

From the AXIS between different columns you can adjust the proportions

Cleanup the plot: edit those placeholder axis to hide labels, titles and legend items

-Jarmo