Wolf, Pajarita and Chantilly came through again about their opinion. Chantilly brought it down to basics.
There is a nest of infertile eggs behind the door to the cockatiel room. What I was told was a male (Tweet) has been laying and sitting on eggs for months now. The last nest that I finally took away from her was filled with dried out eggs. She does not have a mate and there is no way I can stop her.
Take the nest box away. The box encourages them to nest. If they really want to they will find a corner to nest. It will be their choice. If they do you can put the nest box back in and they will follow the eggs. Make it their choice instead of like telling them that here is your nest so fill it up.