Just like a building, it would be great to be able to make an Estate. The reasoning for this is, in our agency we deal with a fair few Industrial Estates and we find that if we were to create the Estate as a building, REX won't allow us to attached properties/listings in that Estate because the building(Estate) needs an address. So clearly this is fine for buildings because the only thing that changes is the Suite or level. With an Estate though each address number is different.
This would be a handy feature for us and other agencies that deal with an Industrial or Residential Estate.