I have a sloping block of land, so the external fence starts on level 1, and runs down to level 0 (in fact below that, but that's ok). So what I'm trying to do is have two exterior walls(fences) that start on one point on level 1, and end on the level below, level 0. It doesn't look possible to me, but if anyone knows how to do that, I'd be most grateful! Thanks, Robert