You can indicate whether a sub-unit is public, sublet, or private for reporting purposes.
Go to Setup > Configuration > Units > Choose your categories and units > then go to your sub-units
Once you are there, go to Options and you can assign the sub-unit a letting status.
Using the Bookings Report, you can hide or show each of these letting statuses for your needs. Great if you just want view the current and expected revenue on everything you are sub-letting.
The letting status column is also displayed when the bookings report is generated.