I'm not sure we're talking about the same route Pierre. I'm talking about the thinner of the two. It sounds a little like you are talking about the fat one (maybe their names are swapped around - I have Tweedledum as the thin one, closest to Lower Tonquani). If I'm not mistaken you are talking about a route just to the right of the splitter crack on the fat one (Crack Attack). It starts with what looks like a sizeable jump to a chicken head? I'm talking about a diagonal line (from left to right) that starts on the thin twin on Upper Tonquani's side. If you walk from Kitchen Corner Gully (Short Gully) towards the twins, it will be the left most arete (for lack of a better word) that you can see. The first chicken head looks like an obelisk and just left and up from it is a gargoyle with a poker chip size hole through it. I don't remember any corners on the thin twin. I'll see if I perhaps have a picture somewhere, to remove all doubt
