You could try covering the eggs with a wire mesh or screen. Alot of folks do this with consistant egg eaters. Are you sure that your discus are eating the eggs or are other fish in the tank helping with that? In my experience I have had spawns in community tanks that met their demise by other fish. If it is in fact your pair that are eating their eggs, it might just be that they are an inexperienced pair and will need time to "get it right" as it goes. Until they do, you could just cover them as described above.
Best wishes!