qmlplugindump, qmldir, multiple plugins registering types to the same namespace.

[bnogal]

The documentation says:
http://doc.qt.io/qt-5/qtqml-modules-qmldir.html
"Zero or more C++ plugin declarations may exist in the qmldir file, however since plugin loading is a relatively expensive operation, clients are advised to specify at most a single plugin."

I have multiple plugins registering types than share same base clases.
Base classes are registered in "root"
inside root/tools/ , i have multiple tools, tool1,tool2, tool3

i was wondering if it would be possible to create a qmldir, than includes all the plugins, and makes them accessible from root.tool
if not, why in qmldir you can specify multiple plugins!, if you can only use the namespace specified on the qmldir, and you cant register new types if the "namespace has already been used for type registration" by the first plugin you indicated in the qmldir file.