In one of my partnerships we play 1♦ openings like in sayc (4+ cards except with 4=4=3=2), but you can also have longer ♣s with less than 16HCP (4♦-5♣ or 5♦-6♣, not 4-6 for example).
We respond 2♣ showing 10+HCP with 4+♣, pretty basic. I'm looking for a good structure, and detailed continuations.
At the moment we play the following:
2♦ = any hand with 5+♦
...responder shows where he has values, usually natural. 2NT is the only NF call, 3♣ shows GF with 6+♣ (we show INV with 1♦-3♣)
2♥ = GF, either ♣ support or balanced 13+-14
...2♠ = relay without 4M
......2NT = 13+-14, bal, GF
......3♣ = GF, 4+♣ support
......3M = extra's, ♣ support, singleton/void M
...3♣ = GF, 6+♣
2♠ = any strength, 4=4=4=1
...2NT = NF
...3♣ = puppet to 3♦ to start slam investigation in whatever suit
...3♦/M = GF, support but no extra's
2NT = min, bal, NF
3♣ = min, ♣ support, NF
3♦ = solid 6+♦
3M = 18-19, bal, 4M, 3OM, 4♦, 2♣
3NT = 18-19, bal, 4=4=3=2
In another thread we found out that the 1♦-2♣-2♦ contains some problems: finding 4-4M fits, showing extra's both as opener as responder, finding 3NT,...
Does anyone have suggestions to improve this structure? Would it be better to play 1♦-2♣ GF? If you play it GF, don't you have problems with invitational hands? Help!

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