The 47k exemption is a total exemption, not one per sibling (though the first 3k of value from each sibling is ignored in a gift situation).
CAT (gift tax) is based on the value of the property being gifted less the amount paid by the person, so, if your brother pays you all enough to ensure his total gift is less than 56k (the 47k plus 3k by 3), no tax will be payable.
Alternatively, if your brother is living in the house (and has been for the last few years) he may be able to take this gift tax free. Alternatively, you might have him move in now (if he does intend on living there) and then delay the separation of the estate until he qualifies for the exemption.