I would definetly remove the moss completely from the roots. This is because in my environment it easily gets waterlogged resulting in negative results for your orchids i.e rot. Theres nothing wrong with sparingly thinly placing it on the surface as this holds humidity. Stick to potting media like large bark or your porous rock or mix them both. media needs to be open to avoid suffocating roots and allows airflow avoiding decomp. Repot gently and dont pack the media too tight. Remember for a rough guide - silver roots mean a drink please, green means had enough for now, wait a couple of days and re assess and brown means rot in most cases. Enjoy your new additions Jan. Our individual grow areas are all different so adapt your care to suit your environment.