IMO,if there were a slam,the bidding sequence would be as belows: (1), [1♠-2♦] [3♦-3♥] [4♣ cue-bid for ♣controls without 6card ♠ (2), [1♠-2♦] [2♠-3♥] [4♣-4♦] cue-bid for ♣&♦,with trump options [? 4♠good ♠ 5♦good ♠ and ♦supports 4♥cue-bid ... Perhaps,there are other good sequences;