[shevek]

This is the auction:

1♣ - (1♠) - ? (Assume 1♠ natural)

Our method is suit transfers here, so

X = tko, not 1-suited
1NT = natural, non-forcing(!) a bit unusual
2♣ = 5+ ♦s, could be weakish, or GF 2-suiter
2♦ = 5+ ♥s
2♥ = GF no major, no stopper
2♠ = 5+ ♣s
2NT = balanced GF

Hoping you can live with that.
What should responder's 3-level bids be?

[Kungsgeten]

Maybe some kind of two-suited bids? Just to get them in there in case the bidding gets high. Something like:

3m = 5+m and 4H, GF. If we first transfer to a minor and then bids hearts, it would show 5-5.
3H = GF 5-5 minors?
3S = Natural, in case of a psyche?
3NT = Transfer. 5+C and 6+H, forcing.
4C = Transfer. 5+D and 6+H, forcing.
4D = Both majors?
4M = Natural, not sure what.

[straube]

Semipositive (nf) with a suit. In this way, responder can transfer at the two-level and rebid his suit forcing.

[foobar]

Straube's suggestion makes sense. BTW, do you intend to handle psyches by trap passing?

[PrecisionL]

What should 3-level responses be?

Using a modified idea of Eric Rodwell:

3♣ = 5♣ + 5 another suit (3♦ asks)
3♦ = 5♦ + 5♥ or 5♠ (3♥ pass/correct)
3♥ = 5♥ + 5♠

[shevek]

PrecisionL, on 2018-January-08, 09:07, said:

What should 3-level responses be?

Using a modified idea of Eric Rodwell:

3♣ = 5♣ + 5 another suit (3♦ asks)
3♦ = 5♦ + 5♥ or 5♠ (3♥ pass/correct)
3♥ = 5♥ + 5♠

That seems okay and easy enough to remember. DONT!

[nige1]

Interference up to 1♠ doesn't take away much bidding space. So Jasmine 1♣ ignores the overcall.
1♣ (1♠) ??

• P_ = NAT. Weak 0-7 HCP or 4+ ♠s.
• X_ = NEG. 8+ HCP. 4+ ♥s.
• 1N = ART. 8+ HCP. 4+ ♥s & 4+ ♠s.
• 2♣ = ART. 0-3 ♥s & 0-3 ♠s.
• 2♦ = ART. 5-7. 6+ suit.
• 2♥ = ART. 2-suiter 5+ 5+ excluding ♥s.
• 2♠/3♣/3♦/3♥ = TFR to good 6+ suit.
• 2N = ART. 5+♥ & 5+ other.