PianoStaff rests

[John Galbraith]

I have a PianoStaff and multi Voice music that hops around it according
to manual staff changes with "\translator Staff = up" or whatever.  Often,
there is no music on one of the staves so it comes up blank (well, it
has barlines and a staff but no notes or rests).    I was wondering if it
is possible to have rests show up as if I typed R4*nnn or whatever 
insteaod of a blank staff.  Actually creating a track with all
multimeasure rests doesn't work, because I don't want to see rests
when there is an active voice on the staff.  Creating a track
that only has rests where nothing else exists is rather tedious - 
it would be more convenient if there was a way to say

"R4*nnn, unless there is other music there from another voice, in 
which case you should \skip over the other voice and resume putting
multimeasure rests when it ends."

Thanks,
        John