Benta,
This idea has something. By doing so, in a way you organise your projects "PCB 'symbols'" in some kind of "superproject"schematic and thus you have the possibility to add orphan components (switches, potmetere, LED's) mounted on the frontpanel or even those cheap Break-out boards. Your schematic becomes the cabling plan.
schould work.
Anyhow, I did not realize the project structure in KiCAD until I did my first DRC. As most people do when reading manuals, I skipped the first 2 or 2 chapters usually telling you how to download and install the software. Maybe it is mentioned there how to set-up a project. Don't know, not longer important.
These remarks/questions are by no means meant to minimize the value of KiCAD: see it as suggestions for improvements/expansion of the good work and if I can contribute to this in any other way, please let me know.