[mw64ahw]

 DavidKok, on 2022-May-14, 02:55, said:

It is very obvious to me that responder should give up on 3NT with ♠xx, ♥Axxx, ♦Jxxxx, ♣xx opposite an unbalanced diamond opening. If opener has a singleton in a black suit we are likely off the first 6 tricks in that suit, and opposite a singleton heart we need partner to have 8 quick tricks to make 3NT. If partner has extra diamond length (so 6(+)) the opponents also have a huge fit and will compete, so you can give up on playing 3NT right away. It's certainly possible that 3NT makes, but it is extremely rare. The rest of the time partner will have some minimum shapely diamond opening and the opponents have a likely spade fit, club fit or both. Put the pressure on right away before they find it.

Not so obvious the way I play it
1♦ - 1♥
1♠ 3+♠ - 1NT I have ♥ (denies ♠)
2NT short ♥ 5431/4144 - 3♦ 5+♦<3♣
Opener now has the choice of final contract depending on hcp distribution, etc.
or even 3NT direct with something like 19+hcp, short ♥ and good control in the black suits

[el mister]

Thanks for all the responses - very helpful.
One follow-up question - if you play a transfer structure over 1♦ - p - 1M - p does it make sense to keep it on with 1 level interference?

Say 1♦ - p - 1♥ - 1♠ back to you. Without the overcall 1N would be clubs, 2♣ would be 6 diamonds, 2♦ would be 3 card H raise etc. Systems on feels right to me but could well be missing something.

[fromageGB]

 mw64ahw, on 2022-May-14, 04:40, said:

Not so obvious the way I play it
1♦ - 1♥
1♠ 3+♠ - 1NT I have ♥ (denies ♠)
2NT short ♥ 5431/4144 - 3♦ 5+♦<3♣
Opener now has the choice of final contract depending on hcp distribution, etc.
or even 3NT direct with something like 19+hcp, short ♥ and good control in the black suits

But as soon as R shows singleton or void hearts, you are going to get a heart lead through your hand and if those exes are truly small, then partner will need to have 8 tricks off the top. While I show hearts initially, when opener denies hearts I give up on NT and just play in diamonds. No way can opener bid NT because he does not know how strong your hearts are.