Ok, there are a few options here for you. Apparently the chinese have now devoloped a strain of parrots that are fertile, but whether yours are or not is yet to be seen. It is possible the eggs went bad because they weren't fertilized... being a first spawn, there really isn't any way to tell.
If you choose to try to tell, you can move the other parrots and Oscar
to another tank for a while if you see eggs again, giving them a fair chance. Being cichlids, the parrots should be good parents if the eggs are healthy.
If raising the fry isn't an issue, pulling the eggs out of the tank should cure the aggressive protective nature of the parent fish.
One other option is to pull the eggs and put those into a quarantine tank to see if they are viable, and hatch them away from the parents. This would avoid the aggression in the main tank and also give the eggs a chance. If attempting to hatch the eggs, you will want to insert a container into the tank, fill it with water and move the eggs into the container and then lift it all out together, avoiding air contact with the eggs if possible. Make the transfer quick, and treat the water in the quarantine tank with methylene blue (check dosing on the bottle) and then put in the eggs. Regular water changes of 20% twice to three times/wk, using newly medicated water to put back into the tank should get you where you need to be for healthy hatching if the eggs are good. To see if the eggs are viable, watch the color within the first 24 - 48 hrs. If the eggs are good they will turn almost an amber color, if not, they will tend to grow a fungus on them right away. You could do all of this in a 10 gallon tank until the eggs hatch and the fry begin to grow, then move up in tank size as they grow. A sponge filter and heater (set for 78 degrees) is all that is really needed, and you can fill the 10 gallon quarantine tank with water directly from the main tank initially. If the sponge filter has spent a few days in the main tank, and moves with the water to the 10, it should be fairly well seeded to keep water quality in good shape and avoid cycling. Be careful not to place eggs directly in air or water flow from filtration but be sure to provide some an air stone near enough to the eggs to provide good water circulation around them, just not directly on/over them.. Do not use a light fixture over the tank with the eggs.
I hope this helps!