使用没有依赖关系的composer

I have project with this scheme:

  • main project depends on subprojects
    • subproject 1 with some own dependencies
    • subproject 2 with some own dependencies
    • subproject 3 with some own dependencies

I'm curious if I can use composer to do job. I would like that packages (subprojects) with type "project" behave like standalone project, not like library.

I found workaround, if in main project composer.json provide/replace all dependencies from subprojects, I can use composer install/update and don't bother about conflicts. I can use custom installer to put subprojects in proper directories and plugin or script to install dependencies for every subproject. This works but is quite hard to maintain, if any subproject adds dependency I need to modify main project composer.json.

Is way to use composer for this task or I should abandon idea write simple tool? What do you think?