Using the 1♠ GF gadget was an approach I picked up from fromageGB. It provides extra bids to shape out and show strength compared to 2♣ In this case: 1♦-1♠ GF 2♥ (4♥6+♦ Min)-3♥ SI (with an MLT of 4.5 this is well within bounds otherwise just place the contract) 3♠ (♠ control)-5♣ (3KCs w. ♣ & ♦ controls and at least 1 ♥ honour) 6♥ (We have the combined strength to make the small slam) Using 2♣ as GF I would bid 4♥ denying the ♦ control or 2♥ honours. North has the strength to then continue the slam bidding. So far I've avoided using frivolous/serious NT/Last train as I find the nuances a touch opaque.