Hi,
The first thing to do is put the cage with the males next to the females. This gives them time to get to know the other birds. Usually this will take several weeks. If they start showing interest through the cages, and even sit near each other, then you can consider putting them in the same cage. Ideally you would put all 4 birds in one large cage to see if they will pair off in male/female pairs. Again, this can take some time. Do not give them any nests or nest boxes. If they do pair up, then move one pair to another cage and give one or both pairs a nest box. You can only have 2 birds in a cage when breeding. If they do bond and breed, then they should be left together even when not breeding. If the males and females do not bond, there is nothing you can do about that. Birds choose their own mates and in the case of the two males, if they are truly bonded, they may not care about the females. In other words, you cannot break up two bonded males, but they may choose to have female mates over their current male companion.
Thank you for asking Lafeber,
Brenda