pulling curves to tighten and loosen based on point

Does anyone know how I might be able to approach tightening a knot or sequences of knots by a single point. I am trying to replicate the ability to tie knots in a string or cable and essentially pull one end to tighten the knot.

I have bee able to "mechanically" draw the spline of the knot but it remains static. I have also tried to offset the curve of the knot to "tighten" it however this becomes problematic if I have a sequence of them as I havent been able to set the parameter that the knots must remain within eachother and not pass though the cable (a physical reality but not so in GH or Rhino)

Firstly though, I am looking for the ability to pull the end of a string or cable that is in the shape of a knot and it become tighter.

Thank, Any help is appreciated.

Alex