Only an audio of Guilty and Woman In Love Demos for Barbra Streisand.
Guilty – Written by Barry, Robin and Maurice Gibb (1979).
Woman In Love – Written by Barry and Robin Gibb (1979).
“Guilty” was the only song for Barbra credited to Barry, Robin and Maurice.
The demo however sounds like the others, and since Barry sings it in falsetto throughout he had probably not yet decided to make it a duet.
This demos were carefully made, with Barry overdubbing two guitars and two vocal tracks at times.
Barbra’s final vocals followed these models closely.
For example the sustained note into the second chorus of “Woman In Love”, very much in Barbra’s style, was sung the same way by Barry on the demo.
Reference : www.columbia.edu/~brennan/beegees