Adding descant measures

I am trying to typeset a song that uses a Closed Score template( in other words T.T.B.B) for the whole song, but for one section of the song there is a descant part that would normally be put up on a staff above the closed score. I don't know how to have that staff for only part of the song. The templates I've tried want to apply it for the entire song. I also tried making the top staff invisible where I don't need it, but this is unsatisfactory because it leaves a barline sticking up from the staff below to where the "ivisible" staff is. I would be glad for any help. Thankyou