Good to Go (TIF) - What destination do I put for a customer going on a mystery cruise?

Unlike TIF, we just cannot automatically select Europe Inc for a customer going on a mystery cruise. 

We will need to get the customer to confirm if their holiday is Europe or WW instead.
 
If they can't, we will have to advise that the only option to ensure that they have full destination cover, is to select WW Including. 
 
I doubt we will get many through GTG, as we are Fred Olsens preferred supplier!