[Hi_Im_Eric]

Playing t-walsh

1c-1d;1h
1h=11-13 bal. or some unbal. hand with 3cH
eg x Kxx AQxx Kxxxx

So if the sequence is 1c-1d;2c
how can I distinguish whether opener have 2cH
eg x Kx AQxx Kxxxxx
Or only have 1cH
eg Kxx x AQxx Kxxxx

[helene_t]

I think you can play 2♠ as relay here. 2♦ is practical as nonforcing, assuming that responder could still have som 10-11 points with six diamonds.

[fromageGB]

Presumably you would have 6 hearts to want to do this. If you are not looking for game, just bid 2♥ to play if you have a singleton or void in clubs, else pass. If game is a possibility or certainty, bid something else which would be taken to be forcing until delayed support is bid. If you have no immediate reply that shows both majors, maybe 2♠ might be taken as a 56xx shape, but it should be forcing, and partner should bid his two hearts for you to go further or not.

Your bidding 2♦ is fine if you have 4 and are not invitational, but it will not get opener to bid his doubleton heart.

[broze]

Do you play 1C 2H as a weak jump? If so, I prefer to have a 2♥ rebid by responder be invitational with 6 (10-12ish depending on opening style).

I think 1C 1D 2C 2D is best used as as an artifical force.