I think you have the wrong perspective on who is the one who "must" do what. They are under no obligation to seek you out to reschedule an interview (although they may attempt to, I've never heard of this). You must initiate this. I'm not sure you're taking the landing interview as seriously as it should be. Ask to reschedule the landing interview, but be prepared to show up to your current interview or else you could end up having your application tossed. Your choice.