Bonded rabbits are rabbits who are 1) both fixed and 2) have been through bonding states, like neutral territory introduction, play dates, etc.
Rabbits do not understand family. Currently you have two rabbits who get along because they are young and hormones have not emerged yet. Once they do, they may fight aggressively. The shift can happen in a day. In the morning they’re cuddling and in the evening it’s a vicious attack due to hormones. Separation until they are fixed and a month after the fixing is what’s required.
Also, depending on how exactly young they are, it’s possible that one or both is actually a male. Sexing rabbits is very difficult. I’d say about 40% of people have a rabbit of the different sex than what they were told.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.