动态附加composer.json文件

I'm writing an application in PHP which should be extensible by some plugins/extensions.

Each plugin should have the possibility to define it's own composer dependencies.

My application is also using a composer.json file to define some dependencies.

Is it possible to define a search path for additional composer.json file in my project's composer.json or maybe define additional search paths on the command line?

I could imagine something like that one:

{
    ...
    "extend" : "extensions/*"
    ...
}

Then every directory inside of my "extensions" path should be searched for a composer.json and the dependencies of it should be automatically installed into the project's vendor folder.