Hi Reiner, sorry I think I misunderstood your question, I thought you were finished with the knotwork part and were working on filling in the middle part.

For getting the over/under knot part, you would indeed need to turn points on (inserting some where necessary) and pull these up in z.

For such a long intricate sweep I think you are probably better off doing all of that before doing the sweep, rather than doing the sweep first and having it update in response to your pulling - like you mention such a long sweep will be rather slow to recalculate.

- Michael