egg laying

my cockatiel had laid few eggs few days back. i candeled the eggs and thinks that they are unfertile. but that time cockateil sits for short span (sits during night), but after her 3 egg she is continously sitting on eggs. can anybody help me weather the eggs are fertile or not.

The parronts of my cockatiel family is living in their own cage and I was trying to avoid putting newspapers simply for covering the droppings but she has been very active, not eating like usual and the male in attack mode (biting harder than usual). It was very obvious that she was going to lay...