Unmerging listings will allow you to assign them separate automation rules for guest messaging and team notifications.
To unmerge listings:
Go to Properties.
Click on the property name.
Click the Remove button to the right of the listing you want to unmerge from this property.
The removed listing will be added to its own property which will appear immediately in the All Properties view.
Note that you will not be able to use the Sync feature for listings that are in separate properties.