HOW to make a piano reduction with multiple voices and rhythms ?

Dear All,   Very clear question:   HOW to make a piano reduction with multiple voices and rhythms ? Like a reduction of a string quartet poliphonic material with 4 voices: ALL RHTYHMS INDEPENDENT with their own pauses. With the typical arrangement of stems for voice separation:   TREBLE CLEF - voice 1 stems up TREBLE CLEF - voice 2 stems down BASS CLEF - voice 3 stems up BASS CLEF - voice 4 stems down   Any help ? Please,
The error is a known problem when you copy and past from html pages. Go to documents and use the original score file. No errors here.