How to build sub c++ project(folder) in a project and how to save dependencies between different projects without session?

[Need4Speak]

1. How to build sub c++ project(folder) in a project?
   -top_pro
   CMakeLists.txt
   -----sub_pro1
   ---------CMakeLists.txt
   -----sub_pro2
   ---------CMakeLists.txt
   If i import top_pro by top_pro's CMakeLists, i can import both sub_pro1 and sub_pro2 at same time, but i can't build sub_pro1 or sub_pro2 alone. Is there any way i can build sub project without import sub_pro1 and sub_pro2 one by one?

2. Qt Creator can set dependencies at project->dependencies, is there any way i can save dependencies without session?

   best regards,
   chao