I read somewhere that it is good to leave your oscars alone for the first time they lay eggs.Some say this will give them a chance to learn to make a sucessful batch of fry .I did this and my first batch went bad due to not being fertilized . Like paul said ,they will turn off white or tanish as i call it if they are fertilized.Some will also get a hairy white fungus and spread to other eggs.I would remove your other 3 fish if you plan to leave the eggs in the tank .If the parents think the fry are in danger they may dispose of the eggs.
another option would be to remove the stump and put it in a smaller tank .Add some Meds to help keep the fungus down and with a bit of luck they should be hatching in about 4 days .
I house two oscars in a 75 gallon and it is really to small.But my house is to small for me also so we are all just gonna have to get by on what we got for now