Adding a smaller lot inside a larger lot. (Like a doughnut) - currently you cannot add a lot that's inside another existing lot ie. the larger lot or polygon's area includes the smaller lot. Whereas the larger lot should exclude the inside smaller lot. Best solution: have an "Exclude Area" button in Edit Polygon/Lot -> pick the Exclude button and snap the the smaller inside polygon/lot and that area is subtracted from the larger lots area.