Printed scores for (especially) major choral works may alternate between one staff per part (i.e., a fugue) or having sopranos and altos sharing a staff with tenors and basses doing likewise for a chorale. This may seem impossible to do in NoteWorthy since a staff is either layered or unlayered for the whole file.
The workaround is to give sopranos and tenors an extra staff each--the top one stands alone and the bottom one is layered with the next part. By using boundary collapse commands and stop boundary collapse commands on either side of a bar line, the two soprano and tenor parts will never be on the printed parts at the same time. They should also share the same midi channel and use the same midi patch (like Choral Aahs).
When two parts share (by layering) a staff, it will be necessary to force stem direction and perhaps slur and tie direction as well. Also, extra space may be needed for notes and/or accidentals when the notes are too close to each other otherwise. See the attachment for an example.