advice needed about biting rabbit

I need some expert advice about my brothers rabbit. Until last Saturday she lived at my house with her sister, but they were separated so that one could be bonded with my own rabbit (which is going along well) and one could go to be bonded with my brothers rabbit at his house. Since arriving there, she(Doris) has been very scared and today my brother told me that she keeps biting him. Doris has always had a nervous temperament but never bitten anyone. She has also bitten my brothers other rabbit(who is also a girl) through the bars of the cages.
Any advice is greatly appreciated!!

It's very difficult to bond 2 female rabbits that haven't lived together since being babies - and it's very sad that the girl sent to live with your brother has been split from her companion rabbit. She will be frightened and pretty unhappy at suddenly losing her friend and going to a new place, so that's why she's behaving badly.

I think you should bring her home and back with her sister - she sounds miserable. Maybe you could bond the 3? Or get another bunny to bond with your existing one/your brother's?

I would definately say to reunite the sisters. They must be really missing one another You could bond the two sisters with your bunny and your brother could go to a rescue and get a friend for his bunny

Hm yes it looks like we might have to do that. Its not very practical atm nor will my brother be very happy. But oh well, these things happen.

tell him how there are zillions in rescues and maybe take him at the weekend to choose one? You could also bond your 3 so they could live happily. I think you need to get that one off your brother before he gets too attached and to make her happy again.