ArtK78, on 2015-January-12, 10:29, said:
The idea of rebidding 2NT holding 5 hearts on the auction 1NT - 2♣ - 2♠ is interesting. We may incorporate it into our structure. Amazingly enough, in all of the years that I have played my current 2-way Stayman structure (about 20 years), this sequence has never come up.
By the way, one poster commented that one should not use the same structure as a passed hand. I am a firm believer that one should not use a weak NT opposite a passed hand, as you are voluntariy opening a balanced minimum hand 1NT opposite a hand that has less than an opening bid. This seems like an invitation to disaster. I note that I have seen a number of prominent players who do open a weak NT opposite a passed hand. I can only assume that their experience is that it is worthwhile to do so.
On the other hand, playing a mini NT opposite a passed hand is downright silly. In those situations where my regular partner and I employ the mini-NT (1st & 2nd seats nonvul), we also open 1 of a suit on all 10 counts. So, if partner is a passed hand, he has less than 10 HCP. Opening a 10-13 1NT opposite a hand known to have less than 10 HCP seems silly to me. We play strong 1NT openings opposite passed hands.
Certainly, some adjustment needs to be made in methods when a weak NT is opened in 3rd or 4th seat. Game force Stayman really doesn't apply anymore as responder can at best only have an invitational hand. That leaves a 2 ♦ response for some other use. For our teammates, a passed hand 2 ♦ response is an August 2 ♦ bid. It asks for opener's longest major to be bid (bidding ♥ if equal). It normally provides a way to run out of 1 NT with a 2 suited hand, but the responding hand could be up to invitational values if holding a 5-5 hand. It provides an assured way to get to at least a 7 card fit if you hold a "garbage" Stayman hand.
I don't see a third seat weak NT as a problem unless we catch partner with a complete bust. Those seem to come a lot less often than everyone fears. OTOH, opening 1 of a minor in 3rd seat certainly makes it easier for the opponents to get in the auction. If the points are fairly evenly distributed, then 1 NT really makes it tough for the opposition to compete.
BTW, just for the record, my favorite partner and I just play a non-forcing Stayman with weak NTs. We play weak NTs in all positions and all vulnerabilities. We don't play transfers. A 2 ♦ response is an August 2 ♦ bid.