My back fence is overhung by trees which stop us being overlooked - they are Firs so hard trimming is not feasible and this makes it impossible to drop in new panels from above! As a result I was thinking about fitting featherboarded fencing. However, the posts do not have slots in the grooves to fit arris rails. Can slots be formed perhaps and if so any ideas? If this is not feasible, any alternative suggestions would be welcome as I wish to avoid re-posting if at all possible.