I do not know much about bonding but something to consider is that brothers and sisters are easier to bond in same gender pairs or groups. I think it is because they already know each others scent. Oh, obviously they have to be spayed/neutered. I have 2 brothers bonded and 3 of their sisters in a group and they get on fine in thier hutches. I put all 5 outside together and normally they are fine, sometimes there is a little dominance humping but never vicious fights. Hope this helps