Many thanks for your very detailed reply. There is a lot of in formation there for me to digest and look into. I had figured out that the external back up should not stay connected to the system and work with 2 backups one of which only gets connected once in a while to bring it up to date. I do back ups on a needs basis as they are not permanently connected. I will do some more reading on FreeFile Sync on how it works and then install it. At the moment we are all supposed to have lots of free time but currently the garden has priority. Once Melbourne's lovely winter weather sets in I will turn my full attention to this.
Once again many thanks for sharing your wisdom. Keep safe. Brigitte