Create a client group with the real estate agency name as the group name.
Create a client and mark them as the primary contact for this group. This may be the real estate agent/agency, or a main point of contact.
Create individual clients for each premises/entity. Set the billing details of each client as the real estate agent or appropriate billing entity.
Set the service address of the client as the property to be serviced.
See Guide: How to Create a Group
Create the real estate agent as a client and set multiple service addresses under them, using the appropriate address per appointment.
Add a note to each address with any specific details for that particular premises.
See Guide: How to Create a Client