When we recorded vocal scratch tracks (for our trio), we each had separate mics, but there is bleed over with the other voices on each of our tracks. Was not previously a problem, as these were only used to rehearse with. One of our trio has now died, is there any way to reduce or eliminate the vocal bleed on these scratch tracks, so hers can be used on a final recording?

very sorry to hear about your losing a band member.
in reaper and other daw packages you could try a noise gate
carefully applied together with mouse editing.
in reaper is also a feature called "REAFIR" that might be usefull carefully applied.
another idea might be there are lots of seasoned people on these forums with audio engineering backgrounds...
thus you could post the audio trak somewhere , and see
if people on these forums could clean it up for you.
there are lots of techniques. sometimes requiring lots of subtle work on a trak.

best
oldmuso