RENDER VSTi multiple outputs

i use say kontakt or omnisphere. some VSTi that has multpile outputs.
so MIDI 1 goes to VSTi 1 out and nuendo knows that because in the inspector MIDI out goes to 1 and VSTi out is set to 1
so WHY not having RENDER only rendering this specific output and not all outputs ?
for the moment when i render MIDI1 i get OUT1 from VSTi but also aaaaaal other outputs to multiple audio track that i have to select/ delete (with the 8.2.1 bug of not beeing able to send audio to trash) then remove the audio empty tracks !