[movingon]

A friend sent this question:

Do you play NMF over interference in either or both of these
> situations: 1C - Pass - 1H - 1S
> 2nt -Pass
> -3D (NMF or second suit?)
>
> 1C - Pass -
> 1H - 2S
> 2nt - Pass
> - 3D (NMF or second suit?)

[helene_t]

You could but I think it is better to make this general agreement:

Whenever some general asking bid (stayman, fsf, nmf, whatever) would apply in an uncontested auction, but the opponents have bid a suit, a bid in opp's suit serves as the general asking bid.

So here 2♦ is natural and 3♠ would ask for 3-card support.

Similarly,

(1♠)-1NT-(pass)-2♣*
is natural: 2♠ would be stayman.

In any case, the most important thing is that you have some kind of general agreement that prevents misunderstanding in situations like this.

[mikeh]

I do not, but that is because I think nmf over a jump to 2N is a poor method. I far prefer transfers.

[P_Marlowe]

Finding the 53 is one task, that gets solved with the help of NMF,
Support Doubles are used to show 3 card support for responders suit,
if they interfere.

With kind regards
Marlowe

[Zelandakh]

I am not sure it is simple as that Helene. You also need to take into account whether a stop has been shown. So the situation after 1♣ - (1♥) - X - (P); 1NT - (P) is different and I think most would keep one or both 2m rebids artificial here rather than using 2♠ for Checkback. As Uwe points out other parts of the system (such as Suport Doubles) matter. And as with Mike I would suggest that transfers over such natural 2NT rebids are generally a better method than NMF.

As an aside, why do you have 2♣ natural there? Would it not make more sense for 2♣ to show diamonds and 2♥ to show clubs? You could also have your cake and eat it too by using 2♣ for both finding a 4-4 heart fit and showing diamonds, perhaps splitting those diamond hands between 2♣ and 2♠ in a logical manner.

[whereagles]

Not sure what the sequences are, but it's normal to play

1m (1x) CALL1 (pass)
1NT (pass) CALL2

if CALL1 = pass, then CALL2 = natural weak
if CALL1 not pass, then in CALL2 NMF applies