The first to die is A. His estate is then to be shared between his brothers, B & C. B then dies - after A, but before A's estate is settled. I do not think this alters the way in which A's estate is distributed - in other words, I think the rules come into play when A died, not when his estate was settled. If this is so, then B's share would be dealt with under B's Will (if he had one) or under intestacy rules (in which case it would all go to his wife unless the complex rules about amounts and limits come into play).