Hidden exclusion parameters can be added to the URL by using the parameter 'tn_parameters_except'.
This is used to exclude certain parameters from the results (show everything except specified parameters)
When filtering by property 'brand' with value 'Coca Cola' or with value 'Pepsi' the value of tn_parameters_except should be:
brand=Coca Cola&brand=Pepsi
This value should then be URL encoded.
Example: ?tn_parameters_except=brand%3DCoca%20Cola%26brand%3DPepsi