System brackets on hidden staves

When setting choral music, I create a system bracket to encompass the voice parts. But if, because of hidden staves, the voice part reduces to a single staff, the bracket is not shown. I believe this is "as designed" but it does not match standard music engraving practices. Is there any way to retain the bracket when the choral system reduces to a single staff? This is especially useful when there is also an unbracketed solo line within the score.