You may create a custom code that will only be applicable for a certain listing.
In that case, the replacement will only occur if your message concerns an inquiry or a reservation for that matching listing. If that is not the case, the custom code will not be replaced by the matching text, and the custom code will be erased from the message.
A custom code must be unique for one listing, but it is possible to create custom codes with the same name for different listings.
For example, you can define a %%nickname%% for each of your listings. The code %%nickname%% will be replaced by the matching text for that listing.