Hi,
I was looking at a video on the forum in which the author folds a thin strip of foam around the thorax which encompasses the wing material and the hackle. Then he wraps thread tightly around all this gathered material horizontally to sort of form a notch to keep the hackle, when wrapped, in a horizontal plane.
After wrapping the hackle, the foam material is trimmed close.
poor explanation, perhaps, but the video is available.
This is what I came up with using his method.