If the other rabbit is a male he will harm the babies
That’s very interesting!I have sometimes put rabbits together in colony-type arrangements, and occasionally lost track and still had the rabbits together when the babies started arriving. I have never seen a buck show any interest in the babies at all, either positive or negative. What I have seen, is the buck relentlessly pursuing the newly-kindled doe, and the doe running around, jumping in and out of the box, scattering and stepping on the babies herself. What I've also seen, is does kindling another litter exactly 31 days later, which isn't a good situation either for her or her kits. So though I have my doubts about whether the buck himself is actually a danger to the kits, I agree, you want to get him out well before the doe's due date.