Hi Reggie,
This is just my personal code for a string quartet I am doing, and my use case may be a little different to normal, as I have to set it all up to be able to do SP->NAT->SP continuous as well as plain SP->NAT, and ST->NAT, and so on, so there are more parts to this than just my initial query MWE. The code was not really proposed as a general purpose solution for this string playing technique.
You're more than welcome to it, but perhaps we should work this up into a more robust and well thought out design pattern for inclusion in the LSR? Also needs to be parameterized to accept sul ponticello or sul tasto.
Andrew