In order to avoid getting a long and empty pentagram at the end of the piece I usually rearrange the spacing of the last line manually, with break lines in the previous systems and space inserts. I often wonder if NWC can do this automatically instead.
Sure you can. Put an extra barline at the end of the top staff, select it, hit <alt><enter>, and choose "Force System Break." Or use the new Insert Boundary Object command and choose "Force a New System" from its dialogue box. In both cases, it will only work if you put the object on the top staff.
Great, thanks William