Hi there,

Unfortunately since they were never spayed it doesn’t sound like they were bonded properly. Given the aggressive nature of the interactions I would separate them (but if they can be near each other, but unable to nip each other, that would be bettter for them). Things could escalate to a full on fight very quickly, as you were worried about.

They likely got along as the daughter was a baby and not hormonal. She is pretty old now, but sometimes things can be fine for a while, but then things start getting testy.

Then you should get them spayed (which should be done for medical reasons anyway, as female rabbits have about 75% rates of uterine cancer by age 4 if not spayed), and allow time for their hormones to settle (several weeks). Then you can go through the bonding process with them.

Dana brings up the most important points. To highlight, rabbits do not acknowledge family units, so whether rabbits are siblings or parent/child, the same bonding procedures must be employed, just like two rabbits who have no blood relation. It seems odd and is one of the most common misunderstandings with rabbits. As Dana stated, the bond you initially observed is more likely because the daughter had no hormones so no territorial instincts were making her act aggressively.