Bonding former friends, separated by introduction of third rabbit

Hello,
My girlfriend and I have 3 bunnies, 2 males (Osho and Luis) and 1 female (Fifi).
At first, the males were bonded. But when we adopted Fifi, the balance was disturbed. Fifi and Osho became inseparable while Luis was pushed aside, and now fights with them both.
Note that all bunnies roam freely in the living room, with a fence to separate the Osho and Fifi from Luis - so they meet regularly.
What can we do to make them all get along? Please help!

Thanks,
Omer and Hadas

Are all bunnies neutered? If so you will have to introduce the 3 in a neutral space and monitor them. As you have 2 boys and 1 female the boys might argue over the female, as they would in the wild. It might work, it might not. Good luck!