Yes they can be together. However I do suggest you separate them into individual pairs for breeding and when they are raising their chicks. Each male will have it's own territory during the breeding season and in bigger very natural looking and planted aviarys they can successfully breed and stay in their own territory but the space required would mean you'd need a rather big aviary. So it's much easier to just have them together until the breeding season. I'd also suggest you get leg bands so you can separate different pairs that you want breeding together.