Hi,
If you haven’t removed the next box, you need to do that. The chicks should be out of it by now and will be weaned soon. They will need to be separated from the parents as soon as they are eating on their own. A pair will fight sometimes when the male is ready to breed again and they still have chicks to care for. You may need to remove him. Sometimes a male will kill the chicks to try to get the female to mate again. Removing the nest box can often stop this behavior. If the female decides to nest and lay eggs before the chicks are weaned, they will let the chicks starve. Right now the hen is still caring for them, which is why she is fighting the male. Once these chicks are weaned and separated, do not give the parents the next box for at least 6 months. Or not at all unless you just want them to be breeders. They do not have to have a nest box or be allowed to breed.
Thank you for asking Lafeber,
Brenda