Defending against multi two diamonds

[rod]

Here's another one from the Coffs Gold Congress teams event.

Match 7, board 7, all vulnerable, South deals. Pauly and I are West and East.

♠ K97532
♥ 7
♦ A6
♣ 10963

♠ AJ6
♥ QJ4
♦ 9753
♣ K42

♠ Q10
♥ K952
♦ KQ4
♣ AQ87

♠ 84
♥ A10863
♦ J1082
♣ J5

The bidding proceeded:

South   West    North   East
Pass    Pass    2♦      Pass
2♥      Pass    2♠      Dbl
Pass    2NT     Pass    3NT
All Pass

2♦ was "multi" showing either a weak two-bid in a major or a strong balanced hand. We don't have a conventional defence to that so I passed to let a natural auction develop.

South's 2♥ was "pass or correct" and North corrected. Now I could make a simple takeout double and 3NT was duly reached.

Then it's up to Pauly to find nine tricks. North led his fourth-best spade. It seems Pauly needs to attack the red suit that South does not have the Ace of, as a spade through while North still has an entry would be fatal. She won the ♠Q and tried a heart from dummy. South played low and the Queen held so it was clear that a switch to diamonds was in order.

When it was over ten tricks were claimed. Nicely done Pauly!

[rod]

That hand got me thinking about a better defense against a multi 2♦ opening. Here's what I think is a good compromise between effectiveness and simplicity:

In Direct Seat:

Double = Takeout for the minors, or a very strong hand.

2NT = Strong and balanced, about 18-20 HCP or as otherwise agreed. Systems are on.

2♥/♠ = Opening values with a good suit.

3♣/♦ = Opening values with a good suit and stoppers in both majors.

Pass = None of the above. You will get another chance to bid so there is no rush to jump in when you need to know what opener's suit is.

After 2♦ - Pass - 2♥:

Here just bid as if the opening was 2♥. If you double, opener will correct if holding spades and partner will act accordingly. Or if you choose to pass with good hearts and opener has spades, you will get a chance to bid your hearts.

After 2♦ - Pass - 2♠:

This would mean that RHO has very good support for hearts and therefore opener is likely to have spades. Similarly to the above, bid as if the opening was 2♠. If you pass with a good spade suit and opener actually has hearts, then you will get a chance to bid again.

After 2♦ - Pass - Pass:

RHO either has a lot of diamonds or is trying to maintain confusion. It's important to protect partner's likely values, so do something with 10 or more HCP. Doubles from here on would be penalty.