Zoops: I'm talking about the first one, though when I first learned this step, I learned it as a milonga pattern that did both. First you would rockstep and forward cross her, she would weight change to her front foot, then you'd "unwrap" her foot around her, and recross.
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So.. the trick is where the follower feels her weight is headed. Lets say you led to her step forward on her left. Now you want her to step
forward with her right, but bring that right foot
behind the left (the usual crossed position) and stop there (not displace the left foot)
The trick is she needs to feel her weight going slightly to
her left so that she doesn't PASS the left foot while stepping forward with the free right foot. I would think the best way to achieve that would be to angle your upper body so that her left side is forward of her right as she takes the step, and also to travel slightly to her left. You could also perhaps help the angle and her "leftward" travel by doing a regular cross yourself for your step. (ie: she's bringing her right foot behind her left in a cross, and at the same time, you are bringing your left foot in front of your right in a cross)
The other trick is to have her feeling the somewhat "left" intention , yet not pass and
then doing a forward ocho to her left to get there. For this issue, the timing is the important key. If you allow her to come straight forward til she gets to or near her "collected" position, chances are her right foot will want to pass the left and ocho, not hook behind it.
Because this is a somewhat "counter intuitive" move for followers, its up to you to lead her so that she can't do anything BUT hook behind. In other words, it has to be
awkward for her to try to pass the standing leg with the free one since that would be her first inclination. OF course, she still might try to do so anyway if she thinks you're just leading badly. But a better follower hopefully has also learned not to sacrifice her own technique, axis, and posture just to compensate for a bad lead. She should go where its
easy to go and if it isn't where you wanted her, you'll realize there's an problem and deal with it.
Too many followers go where they THINK the leader wants them, rather than where the leader actually ends up
putting them, because they are trying to "help out" bad leads. That's why you have to be super-clear and firm when leading something that is unusual for the average follower. They'll figure you're doing something ELSE, but badly, and they'll try to "fix it".
One other reason a follower might not hook her back leg in this crossed position is that if you are NOT hooking or crossing, you may be taking a step yourself that is too long for her to stop in the hooked position. If she feels her weight is still being taken
further forward than crossing will allow, she will either displace her front foot with the hooking one to step again, or quickly unwrap her hooking leg (without ever putting it down) to pass the other leg thinking that she was supposed to do that all along and somehow got it wrong.
So if all you do is come together with your feet, she may not feel enough leftward movement. If you step
back, she may feel she is still being carried forward after she got hooked (and that will confuse her). I think the easiest way is to bring your foot into crossed front. Get a feel for that (and the angle of the bodies) and then work on varying where you place your foot as she hooks behind.