Hi,
My understanding is that you have the whole String section recorded in one track, and you want to divide it by voice, right?
I do the selection manually. With the right Zoom level, it’s quite fast. Then you can use Logical Editor to put all the selected notes into a new track.
You can select the highest note of a chord via Logical Editor. But this one works only if you have chords. It doesn’t work for polyphonic music.