I play 2way nmf. Here is my suggested bidding sequence: 1c-1d (natural, 4+ D) 1nt (balanced hand, does not deny 4 card major, however cannot have 4M+4c)-2nt (gf, 4-4-4-1 with unspecified singleton) 3c (forced) - 3h (singleton H) 3nt (with H stop) -4nt (RKC in clubs, only suit bid so far) 5c (3 key cards) - 7c (worth trying; pass or correct) Admittedly, one minor flaw with this sequence is that if opener happens to have 3-4-3-3, we might be in trouble (he could try 7nt and hope for the best). Otherwise we will find a 4-4 fit grand slam. Remember opener may also have 4-3-3-3, and he will correct to 7s. With 3-3-3-4, or 3/2-4-4 (less likely since he would have opened 1d) 7c or 7d would be the right contract.