If you put the divisi strings on two staves, you can play both voices legato. Don't forget to reserve two channels for these strings on the Manual Sound Sets page and in Vienna Ensemble.
Because of the automatic interval analysis in the legato patches, they can only be monophonic - in all our products. The harmonics included in the Special Edition PLUS you have mentioned are no peformance legati and therefore polyphonic.
The flute legato notes are not looped and so end after some time. In cases where they are too short for you, please exclude the slur from playback as described earlier. Then the sustain patch with looped samples gets triggered.
Andi
Vienna Symphonic Library