I am rewriting my story about big cat friendship for the greater good. I have taken into consideration the fact that friendships between animals that last are usually friendships that started when the animals are babies or when a mom looses all her babies.
So Duma the cheetah cub is being taken care of by a nomadic lioness. At the same time, Anapumua Moto, the lion cub is playing with Bella, the leopard cub. The leopard mom doesn't mind it yet. But when Duma reaches Anapumua Moto and Bella, all 3 big cat moms(so the cheetah mom, lioness, and the leopard mom) start moving towards the cubs and fighting.
There is only 1 option for all 3 cubs to survive and that is to have Duma lead the way to his nomadic lioness caregiver and have the nomadic lioness take care of all 3 until they are old enough to be independent from her.
The problem I see with this is not with the cubs but rather the moms. I think to make this fight believable, all 3 moms should get fatal injuries or at least injuries painful enough to overpower maternal instincts. That would be easy for the cheetah and the leopard but even if the leopard uses gravity and the cheetah uses speed, both to their advantage, I still can't see how the lioness would become injured enough to not go after Anapumua Moto who is at this point with the nomadic lioness.