Yet it is highly likely there are some zoo/s that want females to pair to the males they have!I’d imagine these four girls are adolescent females (offspring of Werribee’s group) that are at the age where it’s time for them to move on.
I wouldn’t be surprised if there was the intention to breed them at Melbourne in the future, but it’s also very possible they could be being moved to Melbourne with the intention of then being housed as surplus females.