As the swans are still young and know each other, it does not hurt to keep several of the same gender together. We are going to share with you the pros and cons of males vs females and then give you are insight on what you might do.
Pros: Can fend for themselves and be better matched if there are any predators in your area as they will be stronger than females.
Cons: Can become rather defensive during mating/nesting season as they will and can pair up with another male especially if they are young and are raised together and no females are available. They will build a nest and sit on the nest until their hormones return to normal. Obviously, they will not produce any eggs.
Pros: Less defensive than the males during mating/nesting season and will accept other swans more readily than the males.
Cons: Can still become somewhat defensive during mating/nesting season as they can and will pair up with another female especially if they are young and are raised together and no males are available. The females can still produce eggs, obviously not viable. They can also get egg impacted from egg laying, but this can happen even if they are paired with a male swan.
These are the basic pros and cons between males and female swans. If you have large predators in the area, you may want to consider staying with the males, although there is no guarantee that they will survive an aggressive attack from a predator any more than a female. The males are just much larger and stronger to help in the fight.
The females will be much more docile than the males. Additionally, with you having 4 females, this will allow all swans to bond to form 2 pairs. With the 3 male scenario, you are going to have an odd man out which can produce many more problems such as fights, injuries, etc.
In the scenario you describe, we would suggest that that you stick with the 4 females so that they can form 2 pairs. This will allow you to re-home the three males so that they have a chance to either form a bond of 2 and then allow the third male to bond with another female or find females for all three.
In the case of re-homing, it must be noted that 2 of the males can be re-homed together if no one wants a breeding male. However, the third male WILL NOT re-pair with another male swan and he will need to be paired with a female swan. Otherwise, you may need to inform the new owners that the three can remain together, but there will be an odd man out. We have seen these types of 3 male siblings work out well and in other cases not work out at all. It totally depends on the individual attributes of the swans. Again, none of the swans will accept another male swan as their mate. They will accept siblings of the same gender, but not a new male swan.
In the event that no one wants the male birds, please contact us and we will try to find a suitable home for all three. The Regal Swan