Un upgrade is always a jce option, though it could be considered a good thing if the tinfoils start to pick off the fry. You dont want 500 little oscar mouths to feed at the best of times.
Sorry they are infertile, but congratulations anyway! If you do get a pair though, and they get fertile eggs and fry, your oscars will keep your tinfoils at the very edge of the tank.
You can tell if eggs are fertile about 18-24 hours into the egg stage, but any less and they all look deceased.
You have 2 possiblities.
1. They have eaten the eggs and will lay more within the next 3 weeks.
2. The eggs have hatched and the fry are in a pit at the back of the tank and will appear in a day or two.
i wonder if oscars will eat their babies after so long? or if oscar babies pick off the weaker smaller fry? hmm. i would be afraid they would mostly survive, and then be over run with oscars.