In Zenu contacts are associated with properties as Owners or Buyers.
All contacts attached to a property as an Owner will remain attached to that recorded as it passes through the Property Timeline unless they are removed.
Once a property reaches the status of Sneak Preview and above you can start to associate contacts with it as potential buyers through enquiries and inspections.
Once a contract is created against a property the contact will be classed as the Purchaser they will remain attached to the property as the Purchaser until removed by cancelling the contract or because the record has been settled and they have been added as the owner of the newly created property record.