Oscars are really intelligent fish, and you never can tell. I have had a few Oscars over the years, I have had to re-home two of them because he/she didn't like anyone, and the other because he/she was so placid that everyone kept picking on the poor thing.
The one I have at the moment is happy with everyone else in the the tanks (a few convicts, a jaguar, a jack dempsey, large leporanos, redhead, small flowerhorn and a pleco) - but he attacks me!
You will probably need to see how you go, and if things don't settle down, you may need to look at moving some of them.
Good luck!